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.