In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: What type of hydrocarbon is coal? Answer: solid
Solid type of hydrocarbon is coal.

Question: Secondary pollutants form from chemical reactions that occur when pollution is exposed to what? Answer: sunlight
Secondary pollutants form from chemical reactions that occur when pollution is exposed to sunlight.

Question: What does a healthy immune system fight off? Answer: infections and other dieases
A healthy immune system fights off infections and other dieases.