Answer is B) 4
When you draw NFA then you will see that its nothing but NFA to accept a string ending with a, having RE $( b . {(a + b)}^* . a)$. This will need only three steps.
But to complete this DFA, we have to design the dead state for state P. because if a string is in the form of $(a.*)$ then it should not be accepted by machine.
Hence total number of states is 4.
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q and s are equivalent states, we can remove any one of them, and one dead state required for missing transition p x a.
