The amino acid which is not optically active is

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $A$ solution of the product obtained by heating a mole of glycine with a mole of chlorine in the presence of red phosphorus generates a chiral carbon atom.
Reason $R$: $A$ molecule with $2$ chiral carbons is always optically active.
In the light of the above statements,choose the correct answer from the options given below:

An example of a sulphur-containing amino acid is:

Proteins function as .......

Which structure$(s)$ of proteins remain$(s)$ intact during the denaturation process?

The artificial sweetener aspartame $(A)$,$H_3N^{+}-CH(CH_2COO^{-})-CONH-CH(CH_2Ph)-COOCH_3$,is converted to . . . . . . on storage for extended periods of time in aqueous solution: