see the basic operation of p1: enqueue and p2: dequeue
statement 1: initial value of f is 0, and it cannot enter p2 until it executes p1. i.e, minimum 1 element should be there before dequeue operation. So this is correct.
statement 3: it can be observed for b that it is used for mutual exclusion. so this is also correct.
however statement 2 is not true for e. See that initial value of e is N. the purpose of semaphore e is to ensure the queue does't overflow. So statement 2 is false.
Hence answer (c)
