The leaves of a plant are made of cells. Each cell has many different cell structures that function together in plant processes. Chloroplasts are cell structures that help in the process of photosynthesis. In this process, chloroplasts use light energy to produce food for the plant. To help chloroplasts absorb more light, the plant grows with its leaves facing upward in the direction of sunlight. Which cell organelle provides the support needed to allow the plant's leaves to be held upright?

A.
mitochondria
B.
nucleus
C.
cytoplasm
D.
cell wall

D. cell wall