The picture (a) is from a organic chemistry book by Clayden, Chapter 32. That means drawing (a) is right expression of the molecule.
What I wonder is that is it possible for (a) to ring-flip? If so, is (b) correct as a ring flip version of (a)? If it's not possible to ring flip, why?
Second question: Is drawing (c) also valid to draw this molecule? If it's so, is it same with (a)? or is it ring flip of (a)? If it's not, what's wrong with it?
Personally, I thought (c) was the right drawing for the molecule. Below (c), I drew the conformation of cyclohexene. The first conformation has a pseudoaxial hydrogen and the inner side of carbon faces downward. This is why I drew (c) with methyl at pseudoaxial, and inner carbon facing downward. But the book only has a drawing of (a).