Q$7.$ Consider the relation $R=\{A,B,C,D,E,F,G,H,$I,$J,K,L,M,N\}$ and the functional dependencies F $=\{\{$C$,$ D$\}->\{$A$,$ B$,$ E$\},\{$C$\}->\{$F$,$ G$\},$

$\{$B$,$ E$\}->\{$I$,$ J$\},\{$F$\}->\{$M$,$ N$\},\{$M$\}->\{$H$\},\{$J$\}->\{$K$,$L$\}\}$

$($a$)(2\%)$ What is the key for $R?$

$($b$)(6\%)$ Decompose R into $2NF,$ then $3NF$ relations.