[" 18.A straight line through a fixed point "(2,3)" intersects the "],[" coordinate axes at distinct points "P" and "Q" .If "0" is the "],[" origin and the rectangle "OPRQ" is completed,then the "],[" locus of "R" is "],[[" (a) "3x+2y=6," (b) "2x+3y=xy],[" (c) "3x+2y=xy," (d) "3x+2y=6xy]]