Aptitude Interview Question:

Given a collection of points P in the plane, a 1-set is a point in P that can be separated from the rest by a line, i.e the point lies on one side of the line while the others lie on the other side. The number of 1-sets of P is denoted by n1(P). The minimum value of n1(P) over all configurations P of 5 points in the plane in general position (.i.e no three points in P lie on a line) is
a) 3
b) 5
c) 2