Infer soil scientists discover that a soil in a valley has a C-horizon of sand that is 1 km deep. is this a transported soil or a residual soil justify your answer.?

This would likely be a transported soil because a 1 km deep sand C-horizon is unlikely to have developed in situ. Residual soils typically have more gradual changes in soil composition and depth compared to the sudden presence of a deep sand layer in a valley. Transported soils are deposited by natural agents like water, wind, or glaciers, and can exhibit distinct layers like the deep sand C-horizon mentioned.