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. 

B. a graduated substance

It would be true sodium reacts with water in a violent way