Two compounds are standing at the same temperature. compound "a" is evaporating more slowly than compound "b." according to the kinetic molecular theory, which assumption can be made?

I think that some options might have helped to answer the question. I am answering the question based on my research and knowledge. "Compound B may have a lower molecular weight" is the assumption that can be made according to the Kinetic Molecular Theory. I hope the answer has come to your help.

Distance^2= yellow line ^2 (see picture) = 30^2 + 49^2so distance = squareroot of (300^2 +49^2)i dont know if this is how to solve it, but i cnt think of another way