Final answer:
The mutation from codon AGA to AGC is a transition mutation, which involves the replacement of one purine with another or one pyrimidine with another without causing a frameshift in the reading frame of the gene.
Step-by-step explanation:
The mutation where a codon is changed from AGA to AGC is known as a transition mutation. This type of mutation involves a purine being replaced by another purine or a pyrimidine being replaced by another pyrimidine. Since both AGA and AGC contain two purines (adenine and guanine) and the third base is a pyrimidine, the replacement of adenine (A) with cytosine (C) doesn't change the structure dramatically, but it still can lead to the change in amino acid depending on the codon's place in the genetic code. The options provided correspond to different types of mutations, but the one described here is specifically a transition mutation, the answer is a) transition mutation.
In contrast, a frameshift mutation involves insertions or deletions that are not evenly divisible by three, which can alter the reading frame of the gene. An example of this would be a deletion or insertion of a single nucleotide into the DNA sequence. A frameshift mutation could lead to a completely different translation of protein due to the change in the reading frame.
An insertion mutation adds one or more nucleotides to the DNA, which can also result in a frameshift if the number of nucleotides inserted is not divisible by three. Whereas a transversion mutation involves a purine being replaced by a pyrimidine or vice versa, which is not the case in the scenario provided in the question.