instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
A frog develops (a/an) lungs as it changes from a tadpole to an adult frog.
answer:
Which of the following structures does a frog develop as it changes from a tadpole to an adult frog?

question:
Seismic waves prove the inner core it is solid.
answer:
What do seismic waves prove about the inner core?

question:
A current is a stream of moving water that flows through the ocean.
answer:
What is a stream of moving water that flows through the ocean?