The velocity of small ball of mass M and density $d_1$ when dropped in a container filled with glycerin becomes constant after some time. If the density of glycerin is $d_2$ then force acting on the ball

Question

\[\begin {array} {1 1} (a)\;Mg (1-\frac{d_2}{d_1}) \\ (b)\; Mg(1+\frac{d_2}{d_1}) \\ (c)\;2Mg (1-\frac{d_2}{d_1}) \\ (d)\;none\;of\;these \end {array}\]