Acountercurrent heat exchanger enables an animal to
a. absorb heat from the environment
b. produce more heat when needed
c. reduce the loss of heat to the environment
d. increase heat loss by evaporation e. slow metabolism when food is not available

A countercurrent heat exchanger (CCHE) enables an animal to c. reduce the loss of heat to the environment. Some animals living in extreme conditions have the ability to maintain their body's heat despite the extreme temperatures of their surroundings. CCHE helps in reducing the heat loss from the skin's surface by means of recycling heat in their bodies. This is usually done by the countercurrent flow of a fluid such as blood.

Covalent bond is the correct answer