The figure below shows the results of a study to determine the effect of soil air spaces on plant growth.

-The data in the above figure indicate that the plant

A)grows best at the lower levels of air in the soil.
B)grows about the same in 15% and 20% soil air levels.
C)grows best in soil air levels above 15%.
D)grows about the same in 15% and 20% soil air levels, and grows best in soil air levels above 15%.
E)grows about the same in 15% and 20% soil air levels, grows best in soil air levels above 15%, and grows best at the lower levels of air in the soil.