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

Ex Input:
Simple carbohydrates can be classified in terms of chain length.

Ex Output:
Which carbohydrates can be classified in terms of chain length?


Ex Input:
Present-day plants that have a complex vascular tissue system are called vasuluar plants.

Ex Output:
Present-day plants that have a complex vascular tissue system are called what kind of plants?


Ex Input:
Estrogen causes the changes of puberty.

Ex Output:

What causes the changes of puberty?