Final answer:
The codon of the mRNA is recognized by the anticodon of the tRNA, and even if a tRNA is modified, it will still recognize the codon specified by its anticodon. So the correct option is c.
Step-by-step explanation:
The codon of the messenger RNA (mRNA) is recognized by the anticodon of the transfer RNA (tRNA). Therefore, the correct answer to the fill-in-the-blank question is the codon and the anticodon. Regarding the reference question, when a tRNA is chemically modified so that the amino acid bound is different from the one specified by its anticodon, it will still recognize the codon specified by its anticodon on the mRNA. This codon-anticodon interaction is essential for correct protein synthesis because tRNAs are charged with amino acids based on their respective anticodon sequences, and they pair with complementary mRNA codons at the ribosome during translation. Even if the tRNA is chemically modified, its anticodon will still base pair with the corresponding mRNA codon.