Which of the following statements about soil formation is true?
a. the longer a soil has been forming, the thinner it becomes.
b. precipitation affects the rate at which nutrients are removed from soil.
c. hot, wet climates produce a thin layer of chemically weathered soil.
d. cold, dry climates produce a thick layer of mechanically weathered soil.

B. Precipitation affects the rate at which nutrients are removed from soil.

Soil is known to be a loose mixture of rock fragments, water, organic materials and air that  usually accommodate the growth of vegetation. Thus, formation and development of soil is a dynamic process rather than static and soil is present when pre-historic animals roamed the Earth and some these animals are preserved only fossilized soils buried deep beneath our present soil.

B. Precipitation affects the rate at which nutrients are removed from soil.

Explanation:

Soil is an aggregate of minerals, gases, water, and organic matter which supports the life of the plants. The soil is formed by the weathering of the rocks. But the formation and development of soil depends upon factors like temperature of the surrounding environment, rainfall and plants growing on it. The rainfall or precipitation can directly influence the quality of the soil. Too much rainfall can lead to leaching or removal of the inorganic and organic nutrients from the soil. They may make the soil acidic.

and after water is usually warmed by the sun the water temperature raises and then evaporates .