This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anatomy
If there are 4 nucleotides instead of 3 in codon, how many amino acids may be formed 
Select and explain. 
A. 4, B. 16, C. 21, D. 256
D: 256
Answer: D: 256 
Explanation: Codons consisting of two nucleotides each could provide for only 16 (42) specific codons, whereas codons of three nucleotides could provide 64 (43) specific codons. Similarly codons with 4 nucleotides could provide 256(44) specific codons