How should you complete this sentence: She had to wait for her car to be repaired, __________ it was in the shop for a week?

The sentence completes logically with "so" because it establishes a cause-and-effect relationship between the need to wait for the car to be repaired and the duration of the repair. Using "so" indicates that the waiting occurred as a result of the car being in the shop for a week. This aligns the two clauses in a way that shows a direct consequence; waiting was necessary because of the lengthy repair time.

While other choices could possibly connect the clauses, they do not convey the same causal relationship. The word "for" would introduce additional information rather than clarify the reasoning, while "and" would simply add another fact without establishing a rationale. "But" implies a contrast, which does not fit the context of waiting due to the car being repaired. Therefore, "so" is the most appropriate choice to complete the sentence effectively.