Question Discussion & Solution

Pushdown automata is used for context free languages, i.e., languages in which the length of elements is unrestricted and length of one element is related to other. To resolve this problem, we use a stack with no restrictions on length. But in the given case, length of stack is restricted. Thus, this pushdown automata can only accept languages which can also be accepted by finite state automata and a finite state automata accepts only regular languages. Thus, B is the correct choice. Please comment below if you find anything wrong in the above post.

The empty stack in the end is our requirement relative to finite state automatons.