Pertaining to demerit-based control charts, which statement is INCORRECT?

Select one:

a.

The occurrence of defects in each class is well modeled by a Poisson distribution.

b.

They are used for dealing with more than one class of independent defects.

c.

c chart is often used for the number of demerits per unit

d.

Each class of defects is weighted differently according to its severity.

e.

None of those listed