Consider the methods used by processors P$1$ and P$2$ for accessing their critical sections when required, as given in the table. The initial values of shared Boolean variables S$1$ and S$2$ are randomly assigned. Which one of the following statements describes the properties achieved and why?

a$)$Mutual exclusion only

b$)$Progress only

c$)$Neither

d$)$Both

Method For P$1$ Method For P$2$

While $($S$1==$S$2)$;

Critical section

S$1=$ S$2$ While $($S$1!=$S$2)$;

Critical section

S$1=$ S$2$