TT D (t) = 10 + 4.9 cos ~t 6 The function D defined above models the depth, in feet; of the water t hours after 12 A.M. in a certain harbor: Which of the following presents the method for finding the instantaneous rate of change of the depth of the water; in feet per hour; at 6 AM ? A D(6)_D(O) 6_0 S 1.633 B D (6) = 0 D"' (6) = 1.343 D(6) = 5.100'