There are two candidate keys of R: {ABGH} and {GHIJ}.
{GHJIK} is not a candidate key, but if it were, then {AGHIJK} would not be a minimal key.
The attribute K isn't part of the two candidate keys, because the closure of {ABGH} contains K, and the closure of {GHIJ} contains K. For example, for {ABGH} . . .
ABGH->ABGH (trivial)
ABGH->IJKF (given), therefore
ABGH->ABGHIJKF
A->CDE (given), therefore
ABGH->ABCDEGHIJKF, or in alpha order
ABGH->ABCDEFGHIJK