The answer to the question is b-Violet ring.

The Bradshaw test is a chemical test used to detect the presence of bile salts in a sample. Bile salts are produced by the liver and are important for the digestion and absorption of fats in the small intestine. The presence of bile salts in a sample can indicate liver dysfunction or other medical conditions.

To perform the Bradshaw test, a small amount of the sample is mixed with a reagent called 2,4-dinitrophenylhydrazine (DNPH) and heated. If bile salts are present in the sample, they will react with the DNPH to form a complex that produces a violet color. This color change indicates a positive result for the presence of bile salts.

Other possible results of the Bradshaw test include a red ring, which indicates the presence of bilirubin, a white ring, which indicates the presence of cholesterol, or a greenish blue precipitate, which indicates the presence of calcium salts.

In summary, a positive Bradshaw test is detected by the formation of a violet ring, which indicates the presence of bile salts in a sample.