The correct structure of glycine at given $\mathrm{pH}$ are

For Aspartic acid  , the  ${\mathrm{pK}}_{{\mathrm{a}}_1},{\mathrm{pK}}_{{\mathrm{a}}_2}$ and ${\mathrm{pK}}_{{\mathrm{a}}_3}$ are $2,4$ and $13$ respectively and for Arginine  , the ${{\mathrm{pK}}_{\mathrm{a}}}_1,{{\mathrm{pK}}_{\mathrm{a}}}_2$ and ${\mathrm{pK}}_{{\mathrm{a}}_3}$ are $2,9$ and $13$ respectively.

 If $\mathrm{pI}$ of aspartic acid is $\mathrm{x}$ and of arginine is $\mathrm{y}$, then $\mathrm{x}+\mathrm{y}$ is:

In the above trimer, if ${\mathrm{R}}_1=\mathrm{H};{\mathrm{R}}_2={\mathrm{CH}}_3$ and ${\mathrm{R}}_3=\mathrm{Ph}$, then total number of optically active stereo isomers will be: