Answer:
But she was able, through revising and revising, to create a thoughtful and sound paper when she needed to do so. The term "sound" mean in this excerpt as (B) Competent.
Step-by-step explanation:
The meaning of the sentence is that the girl can write a thoughtful and knowledgeable paper by revising again and again. So, the word that means ‘sound’ as per this excerpt is Option B, Competent. “Competent’ means one thing that is efficient or something acceptable and decent enough.
Other options are incorrect because Option A ‘fair’ means trustworthy. Option C ‘ample’ means amount of something is enough. Option D ’flimsy’ means breakable. So, these are incorrect options to be used as meaning of ‘sound’.