Question

Some of the largest volcanoes in the solar system are on Mars. The most likely explanation is that Mars 1. has a heavily crated surface. 2. does not possess tectonic plates. 3. has two moons. 4. does not have a magnetic field.

Answer 1

The most likely explanation is 2) Mars does not have tectonic plates.

Think of the Hawaiian islands, which formed as volcanic islands. The accepted theory for their formation is that there was an upwelling of lava from below the earth's crust, and as a tectonic plate moved slowly over that upwelling, it formed the chain of Hawaiian islands. The island of Hawaii itself is the last one in the chain, with a still active volcano. Previously the upwelling built Maui, Lanai, Oahu, etc., and then those volcanos went dormant as the tectonic plate moved past the upwelling.

If the earth didn't have tectonic plates then the same piece of the earth's crust would have sat above the upwelling for a long long time, and the resulting volcano would be very very large. This is basically what happened on Mars.

Answer 2

Mars does not have tectonic plates is really the reasonable answer to your question but the third option also holds good because if mars does not have tectonic plates then from where it generates so much heat to give birth to the largest volcanoes in the solar system. As it has two moons, they provide enough gravitational pull to the mars that it can change the size of it from a spherical planet to an egg size planet. So, this process gives enough heat to the core of Mars to produce these volcanoes.

The largest volcano on Mars is OLYMPUS MONS. It is said that if it gets it summit back then it is 3 times larger in height than the EVEREST mountain.