The candidate key is $AB$.
Consider the proper subset $A$.
We have $A\to DE$.
Also, $D\to IJ$.
$\therefore A^+=\{A,D,E,I,J\}$.
So all of $D,E,I,J$ are functionally determined by the proper subset $A$.
These non-prime attributes belong in an $A$-determined component $: R_2(A,D,E,I,J)$.
Now consider $B$.
$B\to F$ and $F\to GH$.
Thus, $B^+=\{B,F,G,H\}$.
Hence $F,G,H$ depend on proper subset $B$, so we obtain $R_3(B,F,G,H)$.
The attribute $C$ depends on $AB\to C$,
and neither $A$ nor $B$ alone determines $C$.
Therefore, $C$ is fully dependent on the composite key and stays with it $: R_1(A,B,C)$.
Notice that dependencies such as $D\to IJ$ and $F\to GH$ do not force further decomposition for $\text{2NF}$.
Inside $R_2$, $A$ is a single-attribute key, and inside $R_3$, $B$ is a single-attribute key.
Thus all resulting relations are in $\text{2NF}$.
Therefore, the correct answer is A.
