A 25-foot ladder is placed against a vertical wall of a building, with the bottom of the ladder standing on concrete 7 feet from the base of the building. If the top of the ladder slips down 4 feet, then the bottom of the ladder will slide out
(A) 4 feet
(B) 5 feet
(C) 6 feet
(D) 7 feet
(E) 8 feet