Which of the following areas would most likely have the deepest layer of topsoil?

Desert

The loss of top soil in very dry areas of the world is known as desertification. Desertification is the phenomenon in which land degradation of a very dry region increases and the water bodies typically dries up. This also results in not only loss of vegetation but also animal life. This phenomenon can be caused not only due to climate changes, but also due to human activities.

The rocks expand when there hot/warm  and contract when they are cold.