Among the following,the achiral amino acid is

Which of the following statements is correct?

Read the following statements carefully:
$(A)$ Albumin is a simple protein.
$(B)$ The amino acid alanine contains an acidic side chain.
$(C)$ Insulin is a hormone.
$(D)$ Muscles contain the protein keratin.
Point out the wrong statements in the above set of statements.

Which of the following amino acids contains an imidazole ring?

Assertion $(A)$: An optically active amino acid can exist in three forms depending on the $pH$ of the solution.
Reason $(R)$: Amino acids contain both acidic and basic groups; they exist as a zwitterion in aqueous medium,anionic form in basic medium,and cationic form in acidic medium.

The $\alpha$-helix structure is found in: