Identify the statement that is true about coal-bed fires.

A. They are extremely difficult to extinguish because fuel obviously is abundant and oxygen can enter easily, even through joints in surrounding rock.
B. They cannot start from spontaneous combustion; an "outside event" is necessary.
C. They are rare; worldwide, only a handful are currently burning.

A. They are extremely difficult to extinguish because fuel obviously is abundant and oxygen can enter easily, even through joints in surrounding rock.

Explanation:

Coal bed fires refers to spontaneous combustion which are triggered by human activity (mining), lightning, wildfires etc.

This usually happen underground when the coal beds are exposed to oxygen as a result of mining activities or human induced fires or combustion.

The correct answer is B. They cannot start from spontaneous combustion; an "outside event" is necessary

Explanation:

Coal bed fires cannot start from spontaneous combustion; an "outside event" is necessary