Problem: The light from LEDs can be modulated very quickly so they are used extensively in optical fiber and free space optics communications. This includes remote controls, such as for TVs, VCRs, and LED Computers, where infrared LEDs are often used. Opto-isolators use an LED combined with a photodiode or phototransistor to provide a signal path with electrical isolation between two circuits. This is especially useful in medical equipment where the signals from a low-voltage sensor circuit (usually battery-powered) in contact with a living organism must be electrically isolated from any possible electrical failure in a recording or monitoring device operating at potentially dangerous voltages. An optoisolator also allows information to be transferred between circuits not sharing a common ground potential.
Where are opto-isolators found?
The answer is the following: medical equipment

Problem: Houston was incorporated in 1837 under the ward system of representation. The ward designation is the progenitor of the eleven current-day geographically oriented Houston City Council districts. Locations in Houston are generally classified as either being inside or outside the Interstate 610 Loop. The inside encompasses the central business district and many residential neighborhoods that predate World War II. More recently, high-density residential areas have been developed within the loop. The city's outlying areas, suburbs and enclaves are located outside of the loop. Beltway 8 encircles the city another 5 miles (8.0 km) farther out.
What highway circles the outer areas of Houston?
The answer is the following: Beltway 8

Problem: During the 1890s, the Armenian Revolutionary Federation, commonly known as Dashnaktsutyun, became active within the Ottoman Empire with the aim of unifying the various small groups in the empire that were advocating for reform and defending Armenian villages from massacres that were widespread in some of the Armenian-populated areas of the empire. Dashnaktsutyun members also formed fedayi groups that defended Armenian civilians through armed resistance. The Dashnaks also worked for the wider goal of creating a "free, independent and unified" Armenia, although they sometimes set aside this goal in favor of a more realistic approach, such as advocating autonomy.
What was the Dashnaks objective?
The answer is the following: creating a "free, independent and unified" Armenia

Problem: Utrecht city has an active cultural life, and in the Netherlands is second only to Amsterdam. There are several theatres and theatre companies. The 1941 main city theatre was built by Dudok. Besides theatres there is a large number of cinemas including three arthouse cinemas. Utrecht is host to the international Early Music Festival (Festival Oude Muziek, for music before 1800) and the Netherlands Film Festival. The city has an important classical music hall Vredenburg (1979 by Herman Hertzberger). Its acoustics are considered among the best of the 20th-century original music halls.[citation needed] The original Vredenburg music hall has been redeveloped as part of the larger station area redevelopment plan and in 2014 has gained additional halls that allowed its merger with the rock club Tivoli and the SJU jazzpodium. There are several other venues for music throughout the city. Young musicians are educated in the conservatory, a department of the Utrecht School of the Arts. There is a specialised museum of automatically playing musical instruments.
Where are music students educated 
The answer is the following:
Young musicians are educated in the conservatory, a department of the Utrecht School of the Arts