Now consider a single base mutation in a codon for leucine that creates a codon for phenylalanine. a true reversion changes the phenylalanine codon back to a codon for leucine. which of the following leucine codon(s) could be mutated once to form a phenylalanine codon, and then mutated at a second site to restore a leucine codon? select all that apply. (note that two different positions in the codon must be mutated.)1. cuu2. cuc3. cua4. uug5. uua6. cug7. none of these codons