Which of the following is true of a p$-$chart?

a$.$

The lower control limit is found by subtracting a fraction from the average number of defects.

b$.$

The lower control limit indicates the minimum acceptable number of defects.

c$.$

The lower control limit equals D$3$ times p$-$bar.

d$.$

The lower control limit may be at zero.

e$.$

The lower control limit is the same as the lot tolerance percent defective.