Question

How is the excretory system most likely to respond when an animal is thirsty?
a) By relaxing the smooth muscles
b) By retaining body fluids
c) By absorbing heat from lymph glands
d) By releasing hormones

Answer 1

The excretory system is most likely to respond when an animal is thirsty in this way: B. by retaining body fluids.
Because the body doesn't get enough fluids to not be thirsty anymore, it retains whatever fluids it already has in it until the thirst is satiated. 

Answer 2

Answer: b). By retaining body fluids.

Explanation:

An excretory system in animal body secretes excess water, salts, ions and nitrogenous wastes like ammonia from the body. It protects the body from waste aaccumulation.

If the animal is thirsty the excretory system will function to conserve the water in the body by reducing the secretion of bodily fluids like urine from the body. Unless dehydration will result which may lead to failure of organs and death.