Recall the ninhydrin test

Ninhydrin gives a positive test with compounds containing free amino groups (especially $\alpha$-amino acids and proteins having accessible amino groups).

It usually produces a blue-violet color.

Check each option

A: Polyvinyl chloride (PVC)

• PVC is a synthetic polymer of vinyl chloride.
• It does not contain amino groups.
• Hence, it does not give a positive ninhydrin test.

B: Cellulose

• Cellulose is a polysaccharide made of glucose units.
• It contains hydroxyl groups, not amino groups.
• So, it does not respond positively to ninhydrin.

C: Egg albumin

• Egg albumin is a protein.
• Proteins are made of amino acids and contain amino groups.
• Therefore, egg albumin gives a positive ninhydrin test.

D: Starch

• Starch is also a polysaccharide of glucose.
• It has no free amino groups.
• So, it does not give a positive ninhydrin test.

Conclusion

The substance that gives a positive test with ninhydrin is: $\boxed{\text{C: Egg albumin}}$

Comparison with stored correct answer

Stored correct answer = C

My derived answer = C

Hence, they agree.