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 there are 4 nucleotides instead of 3 in codon, how many amino acids may be formed? 
Select and explain. 
A. 16, B. 21, C. 256, D. 64
C: 256
Answer: C: 256 
Explanation: C i.e. 256