The reaction of sulfur burning in oxygen to produce sulfur dioxide is a combustion reaction.

Here's why:

* Combustion is a chemical process that involves the rapid reaction between a substance with an oxidant, usually oxygen, to produce heat and light.

* In this case, sulfur (S) reacts with oxygen (O₂) to produce sulfur dioxide (SO₂).

* The reaction releases heat and light, indicating it is exothermic.

The balanced chemical equation for this reaction is:

S + O₂ → SO₂