Which of the following statements about cell surface receptors is incorrect?

• A. Cell surface receptors can span the entire plasma membrane connecting the exterior and interior cell environments.
• B. Once differentiated, cells cannot change the number or type of cell surface receptors that they possess.
• C. A cell has a wide range of surface receptors to allow it to respond to varying types of signals.
• D. The immune system uses ligands and cell surface receptors to provide immune support for infected tissues.