To solve this problem, we need to analyze each statement about insulin and determine which one is incorrect.$\newline \bullet$Option 1: The proinsulin has an extra peptide called C-peptide.$\newline$ - Proinsulin is the precursor to insulin and contains an additional segment known as the C-peptide.$\newline$ - This statement is correct.$\newline \bullet$Option 2: The functional insulin has A and B chains linked together by hydrogen bonds.$\newline$ - Functional insulin consists of two polypeptide chains, A and B, which are linked by disulfide bonds, not hydrogen bonds.$\newline$ - This statement is incorrect.$\newline \bullet$Option 3: Genetically engineered insulin is produced in E-Coli.$\newline$ - Genetically engineered insulin is indeed produced using recombinant DNA technology in bacteria such as E. coli.$\newline$ - This statement is correct.$\newline \bullet$Option 4: In man insulin is synthesized as a proinsulin.$\newline$ - In humans, insulin is initially synthesized as proinsulin, which is then processed to form active insulin.$\newline$ - This statement is correct.$\newline$Therefore, the statement that is not correct is Option 2.