Problem: While on one hand the Heian period was an unusually long period of peace, it can also be argued that the period weakened Japan economically and led to poverty for all but a tiny few of its inhabitants. The control of rice fields provided a key source of income for families such as the Fujiwara and were a fundamental base for their power. The aristocratic beneficiaries of Heian culture, the Ryōmin (良民 "Good People") numbered about five thousand in a land of perhaps five million. One reason the samurai were able to take power was that the ruling nobility proved incompetent at managing Japan and its provinces. By the year 1000 the government no longer knew how to issue currency and money was gradually disappearing. Instead of a fully realised system of money circulation, rice was the primary unit of exchange. The lack of a solid medium of economic exchange is implicitly illustrated in novels of the time. For instance, messengers were rewarded with useful objects, e.g., an old silk kimono, rather than paid a fee.
What crop became the primary unit of exchange?
The answer is the following: rice

Problem: Comics are a medium used to express ideas by images, often combined with text or other visual information. Comics frequently takes the form of juxtaposed sequences of panels of images. Often textual devices such as speech balloons, captions, and onomatopoeia indicate dialogue, narration, sound effects, or other information. Size and arrangement of panels contribute to narrative pacing. Cartooning and similar forms of illustration are the most common image-making means in comics; fumetti is a form which uses photographic images. Common forms of comics include comic strips, editorial and gag cartoons, and comic books. Since the late 20th century, bound volumes such as graphic novels, comics albums, and tankōbon have become increasingly common, and online webcomics have proliferated in the 21st century.
What type of comic has taken off in the 21st century?
The answer is the following: online webcomics

Problem: Hydrogen, as atomic H, is the most abundant chemical element in the universe, making up 75% of normal matter by mass and over 90% by number of atoms (most of the mass of the universe, however, is not in the form of chemical-element type matter, but rather is postulated to occur as yet-undetected forms of mass such as dark matter and dark energy). This element is found in great abundance in stars and gas giant planets. Molecular clouds of H2 are associated with star formation. Hydrogen plays a vital role in powering stars through the proton-proton reaction and the CNO cycle nuclear fusion.
What percent of normal matter is hydrogen?
The answer is the following: 75%

Problem: The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.
Because of a dog's resourcefulness to people, they have been given what nickname?
The answer is the following:
man's best friend