What is one particular function that the codons (UAA, UGA, or UAG) serve during protein

What is one particular function that the codons (UAA, UGA, or UAG) serve during protein synthesis? Select one: a. UAA, UGA, and UAG are initiator codons, not termination codons. b. They act in chain termination. c. They provide a substrate for the addition of the initiator amino acid. d. These triplets cause frameshift mutations, but are not involved in termination e. They allow the mRNA to assume a variety of linear conformations.