$($a$)$ Consider the relation $R=(A,B,C,D)$ with the following functional

dependencies.

$($FD$1)$ A $$ B

$($FD$2)CD$

$($i$)$ Determine the candidate key$($s$)$ of R$.$

$(2$ marks$)$

$($ii$)$ Determine the highest normal form $R$ is in$.$ Explain your answer. $($For

example, if you think that $R$ is in $3NF,$ then you should explain why it

is in $3NF$ and why it is not in BCNF$.)$

$(3$ marks$)$