<prompt> C- peptide is secreted by ?A cellsB cellsD cellsF cells  <response>: Ans. is b i.e., B cellsInsulin is a polypeptide hormone which is synthesized as a larger preprohormone preproinsulin.Asthepreprohormone enters the endoplasmic reticulum, 23 amino-acid signal peptide is removed and it is conveed to prohormone proinsulin.Proinsulin is made up A and B chain connected by a connecting peptide C-peptide or C-chain.C-peptide is detached in the granules before secretion. Normally, 90-97 of the product released from B cells is insulin along with equimolar amounts of C-peptide.Insulin is a two chain polypeptide having 51 aminoacids : The A chain has 21 while B-chain has 30-aminoacids.Half life of insulin is about 5 minutes. 