Final answer:
The flux observed from a source at a certain distance depends on the source's luminosity and the area over which the light is received, conforming to the inverse square law of light propagation. Option C is correct.
Step-by-step explanation:
The flux seen at a distance from a source depends on both its luminosity and the area over which the observer receives the light. Luminosity is the intrinsic brightness of a source (like a star) and represents the total amount of energy emitted by the source.
The flux we observe on Earth is a result of both the luminosity of the source and the inverse square law for light propagation; the energy gets spread over a larger area as the distance from the source increases.
Furthermore, the flux received by an observer on Earth is the luminosity of the star spread over the surface area of a hypothetical sphere with a radius equal to the distance from the star to the observer, which is also described by the equation L = Ax where L is luminosity, A is the surface area, and x is the energy flux.
The flux seen at a distance from a source depends on both its luminosity and the area over which the observer receives the light. Luminosity refers to the total amount of energy that a source emits, while the area over which the light is received determines how spread out or concentrated the light appears. Therefore, both factors play a role in determining the flux or brightness of a source at a distance.