Teacher: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Earth rotates on its axis once times in one day.
Solution: How many times does Earth rotate on its axis in one day?
Reason: The given output correctly poses a question based on the scientific fact given.

Now, solve this instance: Leaves changing color on trees of these is the best sign that the fall season has begun.
Student:
Which of these is the BEST sign that the fall season has begun?