Answer: A. GUC
Step-by-step explanation:
Looking at the codon chart, we see that on the lower left corner (where first base in codon is G) the whole section matches to amino acid valine. Therefore, GUU, GUC, GUA, and GUG are all correct answers, but since GUC is the only correct choice in the four choices given, GUC is the answer to this question.