Biuret test is used for the detection of
Correct option is A. Saturated oils
$$\text{The Biuret test is a chemical test used for detecting the presence of peptide bonds. indirectly protein}$$ as $$\text{the proteins are made up of amino acids connected together with peptide bonds.}$$
In the presence of peptides, a copper (II) ion forms violet-coloured coordination complexes in an alkaline solution.