A Laser Beam Passes Through a Thin Slit

Multiple Choice

A laser beam passes through a thin slit.When the pattern is viewed on a screen 1.25 m past the slit,you observe that the fifth-order dark fringes occur at ±2.41 cm 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 0.790 cm closer to the central fringe than it was in air.What is the index of refraction of this liquid?

A) 1.33
B) 1.40
C) 1.49
D) 1.62
E) 3.05