57. P and Q are two distinct planes, and P ∩ Q is the set of points common to both P and Q. Which of the following could be P ∩ Q ?

I. No points at all

II. A single point

III. A single line

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

When the two planes P and Q are parallel, I is established. When the two planes P and Q are not parallel, they intersect to form a straight line, and III is established.