You Deposit a Thin Film of Magnesium Difluoride on a Glass

Multiple Choice

You deposit a thin film of magnesium difluoride on a glass lens (n > 1.60) ,reducing the reflection of yellow light,at normal incidence,to a minimum.You find that the thinnest coating that accomplishes this is 106 nm thick.The index of refraction for MgF₂ for yellow light ( $\lambda$ = 585 nm) is

A) 1.50
B) 1.38
C) 1.15
D) 1.00
E) 0.707