Which of the following is the best edit for sentence structure?

The choice that stands out for its superior sentence structure is the one that states successful problem solvers were more adept at both representing the problem and at using heuristics. This option effectively uses parallel structure, which enhances the clarity and fluidity of the sentence.

In this sentence, the phrase "more adept at both representing the problem and at using heuristics" maintains uniform phrasing by using "at" before both components of what the problem solvers are adept at. This consistency captures the reader's attention more effectively and ensures that each part of the sentence is easily understood as contributing equally to the overall meaning.

Additionally, this revised sentence eliminates any potential ambivalence about the relationship between the two skills being discussed. By clearly structuring it this way, the sentence communicates that both skills are of equal importance in the context of successful problem solving.

The other options either disrupt the parallelism or add unnecessary complexity that could lead to confusion.