A rectangle has width w inches and height h inches, where the width is twice the height. Both w and h are functions of time t, measured in seconds. If A represents the area of the rectangle, which of the following gives the rate of change of A with respect to t ?
A. dA/dt=4h in/sec
B. dA/dt=3h dh/dt in^2/sec
C. dA/dt=4h dh/dt in/sec
D. dA/dt=4h dh/dt in^2/sec