Some require less sunlight than others. The trees were planted in different years. Birds are building nests in the shorter trees. The taller trees only have leaves on the top branches.
I gave my students this multiple choice question: Which statement is not a reason why trees would be growing at different heights in a forest?

Only one answer is correct among these 4 choices:
- Some require less sunlight than others.
- The trees were planted in different years.
- Birds are building nests in the shorter trees.
- The taller trees only have leaves on the top branches.

Could you tell me which one is correct?

Birds are building nests in the shorter trees.