Use the Following Two Statements to Answer This Question

Use the following two statements to answer this question:
I. A firm can exert monopoly power if and only if it is the sole producer of a good.
II. The degree of monopoly power a firm possesses can be measured using the Lerner Index:
L = (P - AC) /AC.

A) Both I and II are true.
B) I is true, and II is false.
C) I is false, and II is true.
D) Both I and II are false.