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
Amber codon refers to 
Select and explain. 
A. Mutant codon, B. Stop codon, C. Initiating codon, D. Codon for more than one amino acids
B: Stop codon
Answer: B: Stop codon 
Explanation: Stop codons UAA - ochre; UAG - amber; UGA - opal.