Birds Generate a Lot of Heat, Especially During Flight

Multiple Choice

Birds generate a lot of heat, especially during flight. Yet the adipose tissue under their skin and the feathers atop their skin make it difficult to eliminate excess heat across the skin. Which of the following can absorb body heat and eliminate it from the bird most effectively?

A) lymph in the lymphatic vessels
B) blood in the heart
C) blood in the vessels
D) urine in the bladder
E) air in the air sacs