Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Habitats Nearly all protists exist in some type of aquatic environment, including freshwater and marine environments, damp soil, and even snow. Several protist species are parasites that infect animals or plants. A few protist species live on dead organisms or their wastes, and contribute to their decay. Answer: their decay
Output:
Nearly all protists exist in some type of aquatic environment, including freshwater and marine environments, damp soil, and even snow. several protist species are parasites that infect animals or plants. a few protist species live on dead organisms or their wastes, and contribute to what?