The following two questions refer to the relational scheme R $($A$,$ B$,$ C$,$ D$,$ E $,$ F$,$ G$,$ H$)$

and the following functional dependencies over R:

A $->$ BCD

AD $->$ E

EFG $->$ H

F $->$ GH

$($b$)$ One of the four functional dependencies can be removed without altering the key.

Which one?