D(t)=10+4.9cos(pi/6 × t) D is defined above models the depth, in feet, of the water t hours after 12 am. Which of he following shows 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(0)/ 6-0 = -1.633B) D'(6) = 0C) D'' (6) = 1.343D) D(6) = 5.100