(a) Please discuss how did the progress of technology in the telephone industry affected concentration and competition in the telephone industry over the last 40 years (has concentration increased and competition decrease or has concentration decreased and competition increased). You must give an explanation.

(b)An industry consists of three firms with equal annual sales. (the sales of each of the three firms are the same. What is the industry's HHI and C4? Please show your calculations.

(Hint: You can consider each firm's sales to be S, so that industry sales are 3S)