Which Is Incorrect About the Fc Region of an Immunoglobulin

Multiple Choice

Which is incorrect about the Fc region of an immunoglobulin?

A) Is called the crystallizable fragment
B) Forms the antigen binding sites
C) Contains an effector molecule that can bind to cells such as macrophages and mast cells
D) Contains an effector molecule that can fix complement
E) Determines the class to which the immunoglobulin belongs