Which of the following changes in deciduous forests occurs in the winter?
a. trees regain their leaves.
b. trees block the flow of water and nutrients to their leaves.
c. the leaves of trees begin to lose their chlorophyll.
d. trees live off of stored nutrients.

The correct answer is D. As deciduous forests, on the contrary of evergreen plants, change according to the season, A. (trees regain their leaves) happens only during spring time, B. (trees block the flow of water and nutrients to their leaves), happens during the survival process from wilting, which isn't strictly related to a particular season (other factors intervene, too), C. (the leaves of trees begin to lose their chlorophyll) is the cause for the visible colour change of the leaves during fall season, D. (trees live off of stored nutrients), happens during winter season, due to the lack of sunrays and the harsh weather.