Which counter is a shift register with its complement output of the last stage…

The counter described is a Johnson counter (also known as a Twisted Ring counter or Switch-tail counter).It consists of a shift register where the inverted output Q' of the final flip-flop is fed back into the D input of the first flip-flop. For a register with n flip-flops, a Johnson counter provides 2n distinct states. Unlike a standard Ring counter, which requires n flip-flops for n states, the Johnson counter is more hardware-efficient.