Achair conformation, the equatorial position would be best suited for and the most stable with the presence of

A chair conformation refers to a shape that a molecule might form due to rotation around single bonds. It is most stable when all the atoms in the ring lie in the same plane.

In a chair conformation the there are two types of bonds, equatorial bonds and axial bonds. The equatorial position would be best suited for and most suitable with the presence of methyl groups. this is because methyl group do not interact with other hydrogen atoms present in the structure. 

Iwould say the answer is 4.