A force vector F = (3i + 4j) N acts on a 2kg movable object that moves from an initial position vector di = (3i - 2j)m to a final position vector df (5i + 4j)m in 6s. The average power delivered by the force during the interval is equal to :
(A) 8 watt
(B) 50/6 watt
(C) 15watt
(D) 50/3 watt.