There are four concurrent processes W$,$ X$,$ Y and Z$.$ All have a shared variable $\text{'}$c$\text{'}.$ W and X work as follow reads c from memory, increment by one, store c in memory. Y and Z work as follow reads c from memory, decrement by two, stores into memory. Each process of the four call wait on semaphore s before reading, and calls signal after storing. If semaphore s $=2,$ what is the maximum value of c after all four processes complete execution?

Select one:

a$.-1$

b$.2$

c$.-2$

d$.1$