This is a TM and Not a PDA. The TM reads the input from MSB to LSB in state q0 and does not alter it. On reaching the end of the string the TM changes direction and starts processing charachters from LSB to MSB. On encountering the first one it switches to state q2. From then onwards it starts flipping bits i.e 0 to 1 and 1 to 0. So the given answer is correct.
