Final answer:
The bright streak of light when a meteoroid enters the Earth's atmosphere is created by frictional heating, which causes the meteoroid to vaporize and produce light.
Step-by-step explanation:
The bright streak of light seen as a meteoroid enters our atmosphere is caused by frictional heating as the meteoroid speeds through the gases of our atmosphere. As meteoroids, which are small pieces of rock or debris from space, enter the Earth's atmosphere at high speeds, they encounter air molecules that generate significant heat through friction. This heat causes the meteoroids to burn up or vaporize, producing the vivid flash of light commonly referred to as a shooting star or meteor. It's important to note that meteoroids are different from meteorites, which are the remnants that survive the journey through the atmosphere and reach the Earth's surface. The frictional heating is so intense that even a tiny particle, no larger than a pea, can create a bright light visible from the ground because of the large region of heated, glowing gas that gets formed around it.
The other options a, b, c, and e mentioned in the question are incorrect explanations for the light produced by a meteoroid entering Earth's atmosphere. Such phenomena as sunlight reflection, radioactive decay, magnetic field disturbances, or unusual refraction of sunlight do not account for the observed brightness of meteors.