3

2

1

6

2 input ANDs only

2 input XORs and 4 input AND gates only

2 input NORs and one XNOR gate

NOR gates and shift registers

up-down counter

parallel-counter

shift register

Ripple carry Counter

Combinational circuit alone

Sequential circuit only

Both 1) Combinational circuit alone and 2) Sequential circuit only

None of these

2n

2n-1

n

2n-1