The correct answer is: A. High albedo of clouds, low albedo of water.
The albedo of a surface is its ability to reflect sunlight. The Earth’s surface has a low albedo because it is mostly covered by dark oceans and forests. Clouds, on the other hand, have a high albedo because they are made of water droplets, which reflect sunlight very well. The combined albedo of the Earth and the atmosphere is about 30% because the high albedo of clouds offsets the low albedo of the Earth’s surface.
Option B is incorrect because it states that both clouds and water have a high albedo. This is not true, as clouds have a high albedo while water has a low albedo.
Option C is incorrect because it states that both clouds and water have a low albedo. This is not true, as clouds have a high albedo while water has a low albedo.
Option D is incorrect because it states that clouds have a low albedo while water has a high albedo. This is not true, as clouds have a high albedo while water has a low albedo.