What is step 10 in this proof? A. Statement: Point P lies on line C'D'. Reason: The coordinates of P satisfy the equation of line C'D'. B. Statement: Two of the three medians share point P. Reason: Using point-slope formula C. Statement: Point P lies on line A'E' and line A'E'. Reason: Algebra D. Statement: line A'E' and line A'E' are concurrent. Reason: Definition of concurrence E. Statement: All three lines share point P. Reason: Definition of midpoint