Half-reactions can be written to represent all
(1) double-replacement reactions
(2) neutralization reactions
(3) fission and fusion reactions
(4) oxidation and reduction reactions

Option (4) is the correct answer.

Explanation:

Half reactions are the reactions that represent oxidation and reduction reactions through separate steps.

For example, the oxidation and reduction half-reaction will be as follows.

Oxidation half-reaction:

Reduction half-reaction:

Thus, we can conclude that half-reactions can be written to represent all oxidation and reduction reactions.