Which one of the following is an essential amino acid?

Amino acids are the building blocks of

Each polypeptide in a protein has amino acids linked with each other in a specific sequence. This sequence of amino acids is called . . . . . . structure of that protein.

Identify the correct statement among the following $:$

$A$ codon has a sequence of $\underline{A}$,and specifies a particular $\underline{B}$ that is to be incorporated into a $\underline{C}$. What are $\underline{A}, \underline{B}, \underline{C}$?
$\underline{A} \quad \underline{B} \quad \underline{C}$

The list given below contains essential amino acids that are basic $(X)$ and also non-essential amino acids that are neutral $(Y)$. Identify $X$ and $Y$ from the following list:
$a)$ Lysine
$b)$ Alanine
$c)$ Serine
$d)$ Arginine
$e)$ Tyrosine