A student sees the top edge and the bottom center C of a pool simultaneously from an angle θ above the horizontal as shown in the figure. The refraction index of water which fills up to the top edge of the pool is 4/3. If h/x = 7/4 then cos θ is
(A) 2/7
(B) 8/3√45
(C) 8/3√53
(D) 8/21
