Final answer:
An object of 10 km estimated to hit Earth every 100 million years is most likely a(n) C) Asteroid. Meteor showers are from comet dust streams, meteoroids become meteors, and comets are icy, whereas asteroids are mainly rocky.
Step-by-step explanation:
The object estimated to hit Earth every 100 million years with a size of 10 km is most likely a(n) C) Asteroid. Unlike meteor showers which result from Earth passing through the dust stream of comets, and meteoroids, which are smaller particles that can create meteors by burning up in Earth's atmosphere, an asteroid is a more considerable chunk of rock or metallic material in space. While a comet is primarily made of ice and dust and is recognizable by its glowing coma and tail when it nears the Sun, an asteroid's composition is more rock-based and does not have these visible features. Large impacts from celestial objects such as asteroids happen much less frequently but are significant due to their potential for massive destruction and effects on the global environment.
The object described in the question, which hits the Earth every 100 million years, is an Asteroid.
Asteroids are rocky objects that orbit the Sun, and they are remnants from the early formation of our solar system. Some asteroids have orbits that bring them close to Earth, and they can occasionally collide with our planet.
For example, the extinction of the dinosaurs 65 million years ago is believed to have been caused by the impact of a large asteroid. These impacts can cause significant damage and have long-lasting effects on the environment and life on Earth.