You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
Given a statement, generate a question such that the answer is contained in that statement.

Neurons deliver electrical impulses to other cells
Solution: What do neurons deliver to other cells?
Why? The question generated is valid regarding the information in the statement.

New input: stems are green to protect themselves.
Solution:
What are green to protect themselves?