In the water cycle, animals return water to the environment by a. transpiration only. b. both transpiration and excretion. c. excretion only. d. both respiration and excretion. e. excretion only.

C or E

Explanation:

The answer is excretion only. Excretion is the expelling of waste products, water included. Transpiration is a form of water cycle, but it refers to the evaporation of water from aerial parts and its movement through plants. Respiration is the process of breathing which is mostly separate from the water cycle.