Consider the methods used by processes P1 and P2 to access their critical…

Consider the methods used by processes P1 and P2 to access their critical sections whenever needed. The initial values of the shared Boolean variables S1 and S2 are assigned arbitrarily.

while (S1 == S2);
critical section
S1 = S2;

while (S1 != S2);
critical section
S2 = not(S1);

Which statement describes the properties achieved by these methods?