Which of the following is not true of protein quaternary structure?

The choices for this question can be found elsewhere and as follows:

A. A single polypeptide may have quaternary structure.
B. Hydrogen bonds may hold the polypeptides in contact.
C. A quaternary protein cannot have fewer than two carboxyl groups.

I think the correct answer from the choices is option A. The statement a single polypeptide may have quaternary structure is not true. 

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic