Plants have small holes called stomata on the underside of leaves. Stomata are opened to draw up water from the leaves and allow carbon dioxide in so that the process of photosynthesis can occur. During the process, some water is lost through the open stomata. Based on this information, which stimulus is most likely to cause the stomata to close?

A. Water volume increasing in the soil
B. Water volume decreasing in the soil
C. Carbon dioxide concentration increasing in the atmosphere
D. Carbon dioxide concentration decreasing in the atmosphere