Which of the following gives a positive test with ninhydrin?

The ninhydrin test is a test for amino acids and proteins. Ninhydrin reacts with the free amino groups ($$-NH_2$$) present in amino acids and proteins to give a purple/blue color (Ruhemann's purple).

Among the options:

- Starch: A polysaccharide — no free amino groups. Negative test.

- Egg albumin: A protein — contains amino acids with free amino groups. Positive test.

- Polyvinyl chloride: A synthetic polymer — no amino groups. Negative test.

- Cellulose: A polysaccharide — no amino groups. Negative test.

The correct answer is Option (2): Egg albumin.