In which group would you find a cloaca?

A cloaca is a single posterior opening that serves multiple functions, including excretion and reproduction, and is present in several groups of animals. In amphibians, the cloaca plays a role in expelling waste and gametes during reproductive activities. Reptiles also possess a cloaca that serves similar functions, allowing for the expulsion of urine and feces, as well as the exit for reproductive materials. Mammals generally do not have cloacas, with the exception of monotremes, which are egg-laying mammals like the platypus. Thus, while mammals typically have separate openings, the statement can still hold true when considering the broader classification of mammals, especially when including monotremes. Therefore, all of these groups exhibit the presence of a cloaca, affirming that the correct answer encompasses amphibians, reptiles, and certain mammals.