Samuel tripped while playing basketball and skinned his knee on the concrete. Many of the skin cells on that knee were killed or removed entirely, leaving his knee open and unprotected. Eventually, his knee scabbed over, and when the scabs fell off, there was new skin underneath. Where did the new skin come from? A. Extra skin cells from other parts of Samuel's body were moved to the injury. B. Existing skin cells near the injury reproduced to make new cells. C. Skin cells near the injury increased in size to cover the injury. D. Existing cells near the injury changed into skin cells to cover the injury.