(3) is right.
We perceive an object when light rays (with some colors) from an object reach our eyes.
When light rays, from a source on our side, is reflected from an object then our eyes see the object. This is like a white shirt or white wall.
When light rays from the other side of the object are refracted from that object we see that object. This is for a glass pane on the windows, cars etc.
When light from small water drops in the cloud scatter light rays in all directions, those rays reach our eyes and then we see the clouds. Clouds are not transparent so it means that they do not refract rays. They only scatter light rays in all directions. Since, the clouds are white (given), then all color rays reach our eyes.
So the answer is (3).