Which statement best describes the differences in how flatworms and people remove waste from their body? a. flatworms release carbon dioxide directly from the skin, and use a simple digestive system to remove liquid waste. people use lungs to remove carbon dioxide, and have developed complex excretory and digestive systems to remove waste. b. flatworms do not need to remove carbon dioxide from their body, and do not have a system to remove solid or liquid waste. humans continually remove carbon dioxide and liquid waste from their body. c. flatworms store waste in their bodies until they die. people remove waste through kidneys and lungs.

A. Flatworms release carbon dioxide directly from the skin, and use a simple digestive system to remove liquid waste. People use lungs to remove carbon dioxide, and have developed complex excretory and digestive systems to remove waste.

Explanation:

Flatworms do not have specific organ for gas exchange. The process of diffusion through body surface serves to release carbon dioxide out of the body.  They have gastrovascular cavity which has single opening to serve the function of both mouth and anus.

On the other hand, human have respiratory system with lungs as primary organs to release carbon dioxide out of the body.  They have complex excretory system to remove waste from the body including kidneys and digestive system to digest and absorb the nutrients.