Three identical towels of red, blue and green color are hanging on a clothes line in the sun. What would be the color of shadows of these towels?

Shadow is the dark patch formed when an object obstructs the path of the light. Hence no light reaches in the shadow region; due to which the color of the shadow is black. So the color of shadow is independent of the color of the object because light is always absent there. Therefore the color of shadows of all towels will be black.