AB is a 25-feet high lighthouse, CD is a person of 5 feet height, and DE is the shadow when the beam from lighthouse casts on the person. If this person is walking away from the lighthouse at speed of 2 m/s, what is the rate of change of the length if shadow? 

A. increasing at 2 m/s 
B. increasing at 1 m/s 
C. increasing at 0.5 m/s 
D. decreasing at 0.5 m/s 
E. decreasing at 2 m/s