A Light Ray in Air Strikes a Glass Surface with an Angle

A light ray in air strikes a glass surface with an angle of incidence of $30.0^{\circ}$ . The angle of refraction in the glass is $20.0^{\circ}$ . What is the speed of light in the glass?

A) $1.50 \times 10^{8} \mathrm{~m} / \mathrm{s}$
B) $2.33 \times 108 \mathrm{~m} / \mathrm{s}$
C) $2.50 \times 10^{8} \mathrm{~m} / \mathrm{s}$
D) $2.05 \times 10^{8} \mathrm{~m} / \mathrm{s}$
E) $3.00 \times 108 \mathrm{~m} / \mathrm{s}$