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: Cigarettes are a major source of what kind of chemical substances linked with cancer? Answer: carcinogens
[EX A]: Courtesy of the CDC/Debora Cartagena. Cigarettes are a major source of chemical carcinogens .

[EX Q]: Question: What are prokaryotic cells filled with? Answer: cytoplasm
[EX A]: cytoplasm. Like all other cells, prokaryotic cells are filled with cytoplasm. It includes watery cytosol and other structures.

[EX Q]: Question: What crust is thinner and denser than continental crust? Answer: oceanic
[EX A]:
Oceanic crust is thinner and denser than continental crust.