The volume of a cylinder is calculated as pi*r^2*h. For Cylinder A, this is pi * 3^2 * 4 = 36pi. For Cylinder B, this is pi * 5^2 * 2 = 50pi. Therefore, the ratio of the volumes of Cylinder A to Cylinder B is 36pi/50pi = 36/50 = 18/25. This is Choice A.