Ans is 1 explain please....
Most stable form has lowest potential energy
Where to avoid repulsion groups are on equitorial position
And chair form in more stable than boat unless boat form is stabilised by H bonding
Lowest potential energy means highest stability.
First compare boat and chair form .
Chair form is more stable
Now compare axial and equatorial positions of the chair form .
Equatorial positions groups are more stable
Now pick up the right answer
Chair form is more stable than boat form
So option c,d gone
in b the methyl group on adjacent carbon atom are in cis form
Whereas in A methyl are in trans form .
So in B more repulsion .