Read the paragraph given below and answer the question.

Insulin used for diabetes was earlier extracted from slaughtered cattle and pigs. Insulin from an animal source, though caused some patients to develop allergy or other type of reactions. Insulin consists of two short polypeptide chains: chain A and chain B, that are linked bridges. In mammals, including human, insulin is synthesised as a pro-hormone.

Proinsulin is made up:

(A) Peptide A
(B) Free peptide
(C) Peptide B
(D) Peptide C

Choose the correct answer from the options given below:

(A), (C), (D) only

The correct answer is Option (1) → (A), (C), (D) only