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

i think 1 is correct.we do not know a lot about tectonic plates there as of now

Answer 2

its 3. . The prevalant theory is that due to lack of widespread plate tectonics on Mars.
If Mars lacks plate tectonics, then its clear that a volcano thats created will always remain connected to the magma below. This is because the plates won't move below.
Hence the volcano would keep getting bigger with time.