This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Synthesis of an immunoglobulin in membrane bound or secretory form is determined by: 
Select and explain. 
A. One turn to two turn joining rule, B. Class switching, C. Differential RNA processing, D. Allelic exclusion
C: Differential RNA processing
Answer: C: Differential RNA processing 
Explanation: Ans. is 'c' i.e., Differential RNA processing (Ref: Kuby Immunolo 6th/e, p. 130 - 131)* Differential RNA processing of a common primary transcript determines whether the secreted or membrane form of an immunoglobulin will be produced.* Membrane bound or secreted form of immunoglobulin differs in the amino acid sequence of the heavy chain carboxyl terminal domains.