Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[EX Q]: Question: Which type of arthritis causes the immune system to attack joints? Answer: rheumatoid
[EX A]: In rheumatoid arthritis, the immune system attacks joints. This causes joint damage and pain.

[EX Q]: Question: Protists are the simplest of what? Answer: eukaryotes
[EX A]: Protists are the simplest eukaryotes. They are easiest to define by what they are not. Protists are not animals, plants, or fungi.

[EX Q]: Question: The two main agents of soil erosion are water and what else? Answer: wind
[EX A]:
The main agents of soil erosion are water and wind.