What are the restrictions on the feedforward transfer function G2(s) in the

What are the restrictions on the feedforward transfer function G2(s) in the system of Figure P7.6 to obtain zero steady-state error for step inputs if:

a. G1(s) is a Type 0 transfer function;

b. G1(s) is a Type 1 transfer function;

c. G1(s) is a Type 2 transfer function?