Three materials with n$1<$ n$2<$ n$3$ are arranged in layers of uniform thickness. A light ray in air enters the first layer at an angle of incidence of $30$ and the ray eventually exits the third layer at the refracted angle $$ in air. What is the value of $?$ a$.$ Some angle less than $30.$ b$.30$ c$.$ Some angle more than $30.$ d$.$ Insufficient information to answer