The picture below shows a flower experiencing phototropism, a type of growth movement.



Which of the following best explains the external stimulus that is causing the response in the picture?
A.
The plant, stimulated by light through the window, is responding by growing toward that light.
B.
The plant, stimulated by a need for water, is responding by its roots pushing out of the soil to search for water.
C.
The plant, stimulated by indoor air, is responding by growing toward the preferred outdoor air.
D.
The plant, stimulated by a need for growth, is responding by trying to leave its pot because of lack of space.