I think the answer to your question you ask is the letter b. the second to last.
Answer:
A: US constitution i think. - sorrry if it did not help.
Explanation:
<span>Many factors can affect how long it takes for an inch of topsoil to form, but it normally takes at least 100 years and often over 500 years. The factors that affect soil formation are parent material, topography, climate, organisms and time.</span>
