Final answer:
The speed of light depends on the material it moves through but is independent of the motion of the source and observer. In a vacuum, it remains a constant at 3.00×10^8 m/s and is unaffected by elasticity or inertia.
Step-by-step explanation:
The speed of light depends on the material it traverses. This variation is precise and integral to Einstein's theory of relativity. The Michelson-Morley experiment concluded that the speed of light c is independent of the motion of the source relative to the observer. Thus, contrary to the choices provided, the speed of light is neither dependent on the elasticity nor the inertia of the medium; in fact, light does not require a medium to propagate. In a vacuum, the speed of light is a constant 3.00×108 m/s, and is one of the fundamental constants in nature.