Which of the following gives a positive test with ninhydrin?

Step 1: Ninhydrin Test Purpose — This test specifically reacts with primary $\alpha\text{-amino acids}$ to give a deep blue or purple color.

Step 2: Screening the Candidates — Cellulose and starch are carbohydrates, while polyvinyl chloride is a synthetic polymer. None of these contain amino acids.

Step 3: Identifying the Protein — Egg albumin is a natural protein that yields $\alpha\text{-amino acids}$ after heating or hydrolysis, thus giving a positive ninhydrin test.

Key Point: Ninhydrin is widely used in fingerprinting and protein analysis.