Final answer:
Coal formation is associated with swamps and freshwater swamps, some of which were covered by seawater. Sulfur content in coal can vary depending on the type of environment it was formed in.
Step-by-step explanation:
Coal formation is associated with environments such as swamps and freshwater swamps that existed millions of years ago. In some areas, coal was formed from swamps covered by seawater, which contained a large amount of sulfur. As the seas dried up, the sulfur was left behind in the coal. On the other hand, there are also coal deposits that were formed from freshwater swamps with very little sulfur in them.