11. Countercurrent exchange in the legs of geese
A. facilitates circulation
B. reduces the SMR
C. reduces heat lost to the water
D. increases the energy spent on thermoregulation

Reduces heat lost to the water

Explanation:

In some birds such as the geese, to reduce the amount of energy cost when regulation their temperature, some morphological and behavioural has been used to maintain the rate of heat gain and loss. For uninsulated parts of the birds's body such as the legs, there is the presence to countercurrent head exchange between wherein the arteries and veins in the legs lie in close contact with each other in other to retain heat as these uninstalled regions are potential areas of heat loss since they are uninsulated unlike insulated parts (parts covered with feathers). Constriction of the arteries and veins will ensure blood flow to the feet of the geese at a low temperature.