$30)$ A laser beam passes through a thin slit. When the pattern is viewed on a screen $1\mathrm{.}25$ m past the slit, you observe that the fifth$-$order dark fringes occur at $\backslash (\backslash$pm $2\mathrm{.}41\backslash$mathrm$\{$~cm$\}\backslash )$ from the central bright fringe. The entire experiment is now performed within a liquid, and you observe that each of the fifth$-$order dark fringes is $0\mathrm{.}790$ cm closer to the central fringe than it was in air. What is the index of refraction of this liquid?

A$)1\mathrm{.}33$

B$)1\mathrm{.}40$

C$)1\mathrm{.}49$

D$)1\mathrm{.}62$

E$)3\mathrm{.}05$

Answer: C

Var: $1$