- Ethyl bromide (A) undergoes S\(_N\)2 reaction (bimolecular nucleophilic substitution) because it is a primary alkyl halide.
- Tertiary butyl bromide (B) undergoes S\(_N\)1 reaction (unimolecular nucleophilic substitution) due to the stable carbocation formed.
- Acetone (C) reacts with nucleophiles via nucleophilic addition due to the presence of a carbonyl group.
- Benzene (D) is reactive towards electrophilic substitution because of its aromatic nature.
Step 2: Conclusion.
Thus, the correct matching is:
\[
\text{(A) (I), (B) (II), (C) (IV), (D) (III)}
\]
Final Answer:
\[
\boxed{\text{(A) (I), (B) (II), (C) (IV), (D) (III)}}
\]