$($a$)$ Sitagliptin is a single enantiomer drug that is prescribed to treat Type $2$ diabetes. The chiral centre $($marked with an asterisk $*)$ can be introduced during the synthesis by using a transaminase enzyme as shown below. The reaction proceeds by addition of $-N{H}_2$ to the $Re$ face of the ketone functional group of the carbonyl starting material shown.

$($i$)$ Based on this information, establish the absolute configuration of the chiral amine $C$ that will form. Show clearly how you reached your answer.

C