Question: Read this and answer the question

The Swingle Singers used nonsense words to sound like instruments, but have been known to produce non-verbal versions of musical instruments. Like the other groups, examples of their music can be found on YouTube. Beatboxing, more accurately known as vocal percussion, is a technique used in a cappella music popularized by the hip-hop community, where rap is often performed a cappella also. The advent of vocal percussion added new dimensions to the a cappella genre and has become very prevalent in modern arrangements. Petra Haden used a four-track recorder to produce an a cappella version of The Who Sell Out including the instruments and fake advertisements on her album Petra Haden Sings: The Who Sell Out in 2005. Haden has also released a cappella versions of Journey's "Don't Stop Believin'", The Beach Boys' "God Only Knows" and Michael Jackson's "Thriller". In 2009, Toyota commissioned Haden to perform three songs for television commercials for the third-generation Toyota Prius, including an a cappella version of The Bellamy Brothers' 1970s song "Let Your Love Flow".[citation needed]

What car manufacturer hired Petra Haden to perform a capella songs in commercials for their car?
Answer: Toyota
Question: Read this and answer the question

In the 11th century and the 12th century, the princes and their retinues, which were a mixture of Slavic and Scandinavian elites, dominated the society of Kievan Rus'. Leading soldiers and officials received income and land from the princes in return for their political and military services. Kievan society lacked the class institutions and autonomous towns that were typical of Western European feudalism. Nevertheless, urban merchants, artisans and labourers sometimes exercised political influence through a city assembly, the veche (council), which included all the adult males in the population. In some cases, the veche either made agreements with their rulers or expelled them and invited others to take their place. At the bottom of society was a stratum of slaves. More important was a class of tribute-paying peasants, who owed labour duty to the princes. The widespread personal serfdom characteristic of Western Europe did not exist in Kievan Rus'.

What was the group called that owed labour duty to the princes?
Answer: tribute-paying peasants
Question: Read this and answer the question

Mammalian hair, also known as pelage, can vary in color between populations, organisms within a population, and even on the individual organism. Light-dark color variation is common in the mammalian taxa. Sometimes, this color variation is determined by age variation, however, in other cases, it is determined by other factors. Selective pressures, such as ecological interactions with other populations or environmental conditions, often lead to the variation in mammalian coloration. These selective pressures favor certain colors in order to increase survival. Camouflage is thought to be a major selection pressure shaping coloration in mammals, although there is also evidence that sexual selection, communication, and physiological processes may influence the evolution of coloration as well. Camouflage is the most predominant mechanism for color variation, as it aids in the concealment of the organisms from predators or from their prey. Coat color can also be for intraspecies communication such as warning members of their species about predators, indicating health for reproductive purposes, communicating between mother and young, and intimidating predators. Studies have shown that in some cases, differences in female and male coat color could indicate information nutrition and hormone levels, which are important in the mate selection process. One final mechanism for coat color variation is physiological response purposes, such as temperature regulation in tropical or arctic environments. Although much has been observed about color variation, much of the genetic that link coat color to genes is still unknown. The genetic sites where pigmentation genes are found are known to affect phenotype by: 1) altering the spatial distribution of pigmentation of the hairs, and 2) altering the density and distribution of the hairs. Quantitative trait mapping is being used to better understand the distribution of loci responsible for pigmentation variation. However, although the genetic sites are known, there is still much to learn about how these genes are expressed.

Besides Camouflage being a reason for having certain hair colors, what other reasons have been discovered? 
Answer:
sexual selection, communication, and physiological processes