Ruby-Throated Hummingbirds Migrate as Far North as Northern Canada in the Summer

Ruby-throated hummingbirds migrate as far north as northern Canada in the summer but return to Central America each winter.Migration is extremely energy intensive, and ruby-throats nearly double their body weight (from 3.25 to 6 grams) before migrating.When they reach the Gulf Coast they weigh only about 2.25 grams.What adaptive advantage do these tiny birds receive by making this stressful, hazardous journey every year?

A) There is no adaptive advantage; they merely follow instinct.
B) They evade competition in the northern part of their range.
C) They avoid local extinctions due to bad weather in the tropics.
D) They avoid local extinctions from cold and lack of food in the winter.
E) They are dependent on food in hummingbird feeders along the migration route.