Apo B48 & Apo B100 is synthesized from the same mRNA; the difference between them is due to:

Ans is 'c' i.e. Deamination of cytidine to Uridine.Apo B-48 and apo B-100 are synthesized from the same mRNA.Apo B-100 is synthesized in Liver and forms part of LDL, VLDL and IDL.Apo B-48 is synthesized in Intestines and forms part of chylomicrons and chylomicron remnants.Apo B-100 is the full length translation of corresponding mRNA. Apo B-48 is a shorter form of Apo B-100 (48% of B-100) formed by only partial translation of the same mRNA. It comprises the N-terminal 48% of apo B-100.Apo B-48 is produced due to posttranscriptional mRNA editing in which codon at 2153 position is edited- codon CAA is deaminated to UAA.CAA is a sense codon (coding for glutamine) and deamination changes it to UAA, which is a nonsense codon or stop codon. This stops the translation of mRNA almost midway resulting in a shorter protein B-48 (representing 48 percent of the message).