When a Beam of Light, Originally Traveling in Air, Enters $3 / 2$

Multiple Choice

When a beam of light, originally traveling in air, enters a piece of glass having an index of refraction of $3 / 2$ , its speed

A) is reduced to $2 / 3$ its original value.
B) increases by a factor of $3 / 2$ .
C) is unaffected.