Which describes how outer space, air, and glass affect the speed of light?

a.
light travels fastest through glass, it travels somewhat slower though outer space and of these three, it travels the slowest through air.

b.
light travels fastest through outer space, it travels somewhat slower though air, and of these three, it travels the slowest through glass.

c.
light travels fastest through air, it travels somewhat slower though glass and of these three, it travels the slowest through outer space.

d.
light travels fastest through glass, it travels somewhat slower though air and of these three, it travels the slowest through outer space.