What does the word "conscientious" mean in the following sentence? Although she was conscientious, or careful, a few errors slipped by. A. careless B. determined C. thorough D. smart

I believe the answer is C. thorough.

It's all about context clues. Careful is most similar to thorough and makes the most sense.

The correct answer is C. Thorough

Explanation:

In the sentence presented, the word "conscientious" is used to describe the action of being and acting carefully or without forgetting anything as the sentence explains "she was careful, or conscientious" and the conjunction "or" shows equivalence between these two words, which means the word "conscientious" acts as a synonym of "careful". Therefore, this word most likely means "thorough" that refers to being attentive or careful. This idea is reinforced by "a few errors slipped by" that show despite this woman was conscientious she still has some errors.