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

Input: Consider Input: Potential energy type of energy is possessed by autumn leaves before they fall.

Output: What type of energy is possessed by autumn leaves before they fall?


Input: Consider Input: 600 million many years ago may the earliest fungi have evolved.

Output: How many years ago may the earliest fungi have evolved?


Input: Consider Input: Mars other planet in the solar system is the easiest to observe from earth.


Output: Which other planet in the solar system is the easiest to observe from earth?