instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
The cardiovascular system in the human body consists of the heart, a network of blood vessels, and blood.
answer:
Which system in the human body consists of the heart, a network of blood vessels, and blood?


question:
A diet rich in calcium and vitamin d may reduce the risk of osteoporosis and related bone fractures.
answer:
A diet rich in calcium and what vitamin may reduce the risk of osteoporosis and related bone fractures?


question:
Amphibians (or tetrapods) were the first with four limbs.
answer:

Which vertebrates were the first with four limbs?