[单选题]
A light ray in air is incident on an air to g0:l0a/muoq7 mrqmki; ak5ni,lasz-cr;ze7)pi93 ow qvk3b kqe8v v)(els interface at an angle of $45^{\circ}$ and is refracted at an angle of $30^{\circ}$ to the normal. What is the index of refraction of the glass?
