Here's why:

* Small and circular: Peroxisomes are indeed small, membrane-bound organelles with a generally round or oval shape.

* Contains enzymes: Peroxisomes are packed with enzymes that carry out various metabolic functions, including:

* Breakdown of fatty acids: They contain enzymes for beta-oxidation of fatty acids, producing hydrogen peroxide as a byproduct.

* Detoxification: They detoxify harmful substances like alcohol and reactive oxygen species.

* Synthesis of lipids: Peroxisomes are involved in the synthesis of certain lipids, such as plasmalogens.

While other organelles also contain enzymes, the combination of small, circular shape and specific enzymatic activity points to peroxisomes as the most likely answer.