Beta-oxidation is
the breakdown of sugars
the assembly of sugars
the breakdown of fatty acids
the removal of amino groups from amino acids

the breakdown of fatty acids is a correct answer.

Explanation:

Beta-oxidation is  the breakdown of fatty acids.

Beta oxidation is a process in which fatty acids are break down in the cytosol (prokaryotic cells) and in mitochondria(eukaryotes cells) to produce energy.beta-oxidation is the  metabolic process in which the fatty acids gets oxidized,it takes occur in four steps dehydrogenationhydration oxidation thyolisis.Beta oxidation results in the formation of acetyl-CoA and ATP.

Thus Beta-oxidation is  the breakdown of fatty acids.