In the figure shown, light waves A and B both of wavelength `lambda` are initially in phase and travelling rightward as incident by the two rays. Wave A is reflected from four parallel surfaces but ends up travelling in original direction. The possible value(s) of distance L in terms of wavelength `lambda` in figure which put A and B exactly out of phase with each other after all the reflected is/are

Options

A. `lambda//2`
B. `3lambda//2`
C. `3lambda//4`
D. `lambda`

Answer

C