Answer the following question given this paragraph: 

All amphibians have digestive, excretory, and reproductive systems. All three of these organ systems use a single body cavity, called the cloaca. Wastes enter the cloaca from the digestive and excretory systems. Gametes enter the cloaca from the reproductive system. A single external opening in the cloaca allows the wastes and gametes to exit the body. (Many other four legged vertebrates also have a cloaca. ).


Q: An external opening in the what of amphibians allows wastes and gametes to exit the body?


A:
cloaca