Which of the following statements regarding PERT times is TRUE?

Select one:

A$.$ The pessimistic time estimate is an estimate of the minimum time an activity will require.

B$.$ The optimistic time estimate is usually the same as the most likely time estimate.

C$.$ The optimistic time estimate is an estimate of the maximum time an activity will require.

D$.$ The expected time estimate is calculated as $t=\frac{a+4m+b}{6}.$