Answer:
D. ACA codon codes for threonine
Explanation:
The genetic code has 64 triplets of nucleotides, each one is called codon. Each codon except three of them, encodes for one of the 20 amino acids used in the process of synthesis of proteins
ACA, ACG, ACC and ACU are the only codons of the genetic code able to code for threonine. The codon UCG codes for serine, the codon UGU codes for cysteine and the code CGA codes for arginine
