Which out of the following amino acid is a precursor of niacin (Vitamin)?

Q. Which out of the following amino acid is a precursor of niacin (Vitamin)?
A. Tyrosine
B. Threonine
C. Tryptophan
D. Phenylalanine
Answer: Tryptophan

A. Tyrosine
B. Threonine
C. Tryptophan
D. Phenylalanine
Answer: Tryptophan