This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
If constitutive sequence of 4 nucleotide codes for 1 amino acid, how many amino acids can be theoretically formed? 
Select and explain. 
A. 4, B. 64, C. 16, D. 256
D: 256
Answer: D: 256 
Explanation: Codon -The triplet nucleotide sequence present in the mRNA representing specific amino acid:

If 1 base represent 1 amino acid, only 4 amino acid.
If 2 base represent 1 amino acid, 42 amino acids, i.e. 16 amino acids.
If 3 base represent one amino acid, 43 i.e. 64 amino acids.
If 4 bases represent 1 amino acid, 44 i.e. 256 amino acids.

Reference- Harper 30th edition Pg- 415