Consider the following empty stack PDA, where state 0 is the initial state and $ is the initial stack symbol: <0, a, $, push(X), 0> (Rule 1) <0, a, X, push(X), 0> (Rule 2) <0, b, X, pop, 1> (Rule 3) <0, , $, pop, 2> (Rule 4) <1, b, X, pop, 1> (Rule 5) <1, a, $, push(X), 0> (Rule 6) <1, a, X, push(X), 0> (Rule 7) <1, , $, pop, 2> (Rule 8) Which string is accepted by the above PDA? A. a B. b C. ab. D. aba