A variable line passing through the origin intersects two given straight lines 2x + y = 4 and x + 3y = 6 at R and S respectively. A point P is taken on this variable line. Find the equation to the locus of the point P if?

A) OP is the arithmetic mean of OR and OS.
B) OP is the geometric mean of OR and OS.
C) OP is the harmonic mean of OR and OS.