This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
To synthesize insulin on a large scale basis, the most suitable staing material obtained fro the beta cells of the pancreas is: 
Select and explain. 
A. Genomic DNA, B. Total cellular RNA, C. CDNA of insulin, D. MRNA of insulin
D: MRNA of insulin
Answer: D: MRNA of insulin 
Explanation: D i.e. mRNA of insulin Insulin is synthesized on a large scale basis from complementary DNA's (cDNA), using recombinant technology. But cDNA is not the staing material. cDNA are derived from mRNAQ.Thus mRNA is staing material for insulin synthesis on a large scale basis.Construction of cDNA from mRNA