Critical Reasoning

When old-grow forests are cleared of tall trees, more sunlight reaches the forest floor. This results in a sharp increase in the population of leafy shrubs on which the mule deer depend for food. Yet mule deer herds that inhabit cleared forests are less well-nourished than are herds living in old-growth forests.

Which one of the following, if true, most helps to resolve the apparent paradox?

(A) Mule deer have enzyme-rich saliva and specialized digestive organs that enable the deer to digest tough plants inedible to other deer species.

(B) Mule deer herds that inhabit cleared forests tend to have more female with young offspring and fewer adult males than do other mule deer populations.

(C) Mule deer populations are spread throughout western North America and inhabit hot, sunny climates as well as cool, wet climates.

(D) As plants receive more sunlight, they produce higher amounts of tannins, compounds that inhibit digestion of the plants' proteins.

(E) Insect parasites, such as certain species of ticks, that feed primary on mule deer often dwell in trees, from which they drop onto passing deer

OA is D
Could the OA be correct? Urgent answer from an Expert please.