A normal queue, if implemented using an array of size MAX_SIZE, gets full when?

A normal queue, if implemented using an array of size MAX_SIZE, gets full when?
a. Rear = MAX_SIZE – 1
b. Front = (rear + 1)mod MAX_SIZE
c. Front = rear + 1
d. Rear = front

Answer:
A. Rear = MAX_SIZE – 1

When Rear = MAX_SIZE – 1, there will be no space left for the elements to be added in queue. Thus queue becomes full.