b$.$ Consider the universal relation $R=\{A,B,C,D,E,F,G,H,$I,$J\}$ and set of

functional dependencies:

FD$1$: $\{A\}\{D,E\}$

FD$2$: $\{B\}\{F\}$

FD$3$: $\{F\}\{G,H\}$

FD$4$: $\{D\}\{I,J\}$

$($i$)$ The Key of the relation $R$ is $\{A,B\}$

$($ii$)$ Decompose $R$ into $2NF$ and $3NF.$