Which of the following best compares the relationships of mutualism and commensalism?

A.
In mutualism, one organism is harmed; whereas in commensalism, two organisms are harmed.

B.
In mutualism, one organism benefits; whereas in commensalism, two organisms benefit.

C.
In mutualism, two organisms are harmed; whereas in commensalism, one organism benefits.

D.
In mutualism, two organisms benefit; whereas in commensalism, one organism benefits.

PLEASE HELP