Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[Q]: Some viruses carry a few viral enzyme molecules within their capsids.
[A]: Some viruses carry a few viral enzyme molecules within their what?

[Q]: The cardiovascular system in the human body consists of the heart, a network of blood vessels, and blood.
[A]: Which system in the human body consists of the heart, a network of blood vessels, and blood?

[Q]: Conductivity, oxidation state and physical appearance are properties that help determine whether elements are metals.
[A]:
Conductivity, oxidation state and physical appearance are properties that help determine whether what are metals?