Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Viruses , like the one depicted in Figure below , are tiny particles that may cause disease. Human diseases caused by viruses include the common cold and flu. Do you think viruses are prokaryotes or eukaryotes? The answer may surprise you. Viruses are not cells at all, so they are neither prokaryotes nor eukaryotes. Answer: viruses
[EX A]: The common cold and flu are examples of human diseases caused by what tiny particles?

[EX Q]: Passage: Some resources can't be renewed. At least, they can't be renewed fast enough to keep up with use. Fossil fuels are an example. It takes millions of years for them to form. We are using them up much more quickly. Elements that are used to produce nuclear power are also non-renewable resources. Uranium, for example, which is rare. Sooner or later, it will run out. Answer: nuclear
[EX A]: Uranium is an example of a non-renewable resource used to produce what type of power?

[EX Q]: Passage: The burner on a gas stove burns with a pretty blue flame like the one pictured in the opening image. The fuel burned by most gas stoves is natural gas, which consists mainly of methane. Methane is a compound that contains only carbon and hydrogen. Like many other compounds that consist of just these two elements, methane is used for fuel because it burns very easily. Methane is an example of a covalent compound. Answer: methane
[EX A]:
Natural gas, such as those burned by gas stoves, is composed mostly of this?