This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Codon consist of 
Select and explain. 
A. 3 base pair, B. 2 base pair, C. Two nucleotide, D. 5 base pair
A: 3 base pair
Answer: A: 3 base pair 
Explanation: DNA is a reference for proteins, which are the functional molecules in cells. These are comprised of 20 unique amino acids, and each is coded for by a stretch of DNA known as a codon. Codons are always 3 base-pairs (nucleotides) in length.Ref: Harper&;s Biochemistry; 30th edition