Monochromatic light with wavelength $\lambda$ falls on two narrow slits $S_1$ and $S_2$, separated by a small distance. A sequence of bright and dark fringes appears on a screen far from the slits. The $n$th dark fringe away from the central bright fringe is seen at point P on the screen. Which equation is true for every positive value of $n$?
- A$S_2P - S_1P = \frac{n\lambda}{2}$
- B$S_2P - S_1P = n\lambda$
- C$S_2P - S_1P = \left(n - \frac{1}{2}\right)\lambda$
- D$S_2P - S_1P = \left(n + \frac{1}{2}\right)\lambda$