Which of the following represents the intersection of two planes?

Question

a line

a point

two points

a point or a line

Answer 1

a) unless they are parallel.In this case they have nothing in common

Answer 2

It depends on the dimension of the space in which the two planes lie. In 3-dimensional space, (assuming they are not parallel or the same plane), two planes intersect in a line; but in 4-d space, in general two planes intersect in one point. (In 5-space and above two planes in general do not intersect. This is advanced level geometry and should only be considered by students of the geometry of n dimensions.)

You probably are working in 3-space, so line is the answer then.