Most Insects Use External Sources of Heat to Achieve Their

Most insects use external sources of heat to achieve their operative temperature range. Heinrich's research on the sphinx moth (Manduca sexta) indicates that some insects can thermoregulate by using their flight muscles and

A) using their blood as a coolant.
B) decreasing their metabolic rate.
C) possessing an internal respiratory system.
D) using a countercurrent heat exchange mechanism.
E) using a concurrent heat exchange mechanism.