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

[EX Q]: Passage: In many ways, humans are unique among mammals. For example, we have bigger brains and a greater ability to learn than any other species in the mammalian class. In many ways, however, we are typical of the mammalian order to which we belong. That order is the Primate Order. To fully understand what it means to be human, you need to know more about this fascinating order of mammals. Answer: humans
[EX A]: What mammalian class has the greatest ability to learn?

[EX Q]: Passage: For example, remember that for the height gene in pea plants there are two possible factors. These factors are alleles. There is a dominant allele for tallness (T) and a recessive allele for shortness (t) . Answer: alleles
[EX A]: What factors determine the effect of a gene?

[EX Q]: Passage: Water is the only substance on Earth that is stable in all three states. Answer: water
[EX A]:
What is the only substance on earth that is stable in all three states?