Select the postulate that proves this fact. if g and h are different points in plane r, then a third point exists in r not on gh. postulate 1: a line contains at least two points. postulate 1a: a plane contains at least three points not all on one line. postulate 1b: space contains at least four points not all on one plane. postulate 2: through any two different points, exactly one line exists. postulate 3: through any three points that are not one line, exactly one plane exists. postulate 4: if two points lie in a plane, the line containing them lies in that plane. postulate 5: if two planes intersect, then their intersection is a line.