At the profit-maximizing level of output, what is relationship between

At the profit-maximizing level of output, what is relationship between the total revenue (TR) and total cost (TC) curves?

A) They must intersect, with TC cutting TR from below.
B) They must intersect, with TC cutting TR from above.
C) They must be tangent to each other.
D) They cannot be tangent to each other.
E) They must have the same slope.

ANSWER

E