In an isosceles triangle PQR, if the measure of angle P is 80, which

In an isosceles triangle PQR, if the measure of angle P is 80, which of the following could be the measure of angle R ?

I. 20
II. 50
III. 80

(A) Only I
(B) Only III
(C) Only I and II
(D) Only II and III
(E) I, II and III