If the rate of seafloor spreading was faster than the rate of subduction than we would have had much more land mass on the surface on the Earth. This will cause lots of very long and very high mountain ranges in the oceans (much bigger ones that the ones that are forming now) and because of the huge amount of magma that will be pushing through they will be getting above the ocean waters and forming new land masses, and that will make the world much different from what we now it now.
Three things than can cause erosion are wind, water, and flames
Answer:
Is the object made of ice and dust? If so, it is likely a comet.
Explanation:
Comets are the bodies of the solar system that have the smallest diameter in relation to other bodies. Each comet has its divinity structure in the nucleus, hair and tail and its composition is composed of rock, dust and ice. This ice is quite dirty, because of all the dust and can make up most of the comet, reaching dozens of tons, but it can also be presented in smaller quantities.
Probably B. Hope that helps, if that's correct:)