Consider the following four$-$step process:

pic$8$

The following data are available for the four steps:

A B C D

Activity time per unit $($min$)0\mathrm{.}250\mathrm{.}330\mathrm{.}20\mathrm{.}5$

Capacity per worker $($units$/$min$)4352$

Number of workers $2324$

What is the capacity of the process?

a$.$

$2$ units$/$min

b$.$

$8$ units$/$min

c$.$

$5$ units$/$min

d$.$

$10$ units$/$min