A Double-Slit Interference Experiment Is Performed in the Air

Multiple Choice

A double-slit interference experiment is performed in the air. Later, the same apparatus is immersed in benzene (index of refraction, n = 1.50) , and the experiment is repeated. When the apparatus is in benzene, you observe the interference fringes to be

A) more closely spaced as when the apparatus is in air.
B) equally spaced as when the apparatus is in air.
C) more widely spaced as when the apparatus is in air.
D) Impossible to tell without knowing the wavelength of light in use.
E) Impossible to tell without knowing the separation between the slits.