The phases of the light wave at c, d, e and f are $$\phi_C, \phi_d, \phi_e$$ and $$\phi_f$$ respectively. It is given that $$\phi_c \neq \phi_f$$.

A

$$\phi_c$$ cannot be equal to $$\phi_d$$

B

$$\phi_d$$ can be equal to $$\phi_e$$

C

$$(\phi_d - \phi_f)$$ is equal to $$(\phi_c - \phi_e)$$

D

$$(\phi_d - \phi_c)$$ is not equal to $$(\phi_f - \phi_e)$$