Ji wants to write an example of a frameshift mutation using the following sentence: THE CAT SAW THE RAT. Which sentence best shows a frameshift mutation?

A frameshift happens when letters are inserted or deleted, changing how the remaining letters are grouped. The original sentence has the letters THECATSAWTHERAT; choice A removes the E from THE, leaving THCATSAWTHERAT, which shifts the later groups. Choice D adds three letters, so it does not shift the grouping in this analogy.

AI-written and checked against the verified answer.