Four light sources produce the following four waves :
i. `y_1 = a' sin (omegat + phi_1)`
ii. `y_2 = a' sin (2 omegat)`
iii. `y^3 = a' sin (omega t + phi_2)`
iv `y_4 = a' sin (3 omega + phi)`
Superposition of which two waves give rise to interfernce ?

Options

A. I and II
B. II and III
C. I and III
D. III and IV

Answer

C