The correct answer is B. Rewriting sentences that stray from the focus of the paragraph
Step-by-step explanation:
The paragraph presented starts with a topic sentence that is "Popcorn first gained popularity in the United States during the Great Depression", after this sentence the author explains the circumstances in which this occurred by stating popcorn was a cheap alternative to sweet candies that were expensive during this period. Then the author claims people used to add salt and butter to make popcorn delicious, but this had negative effects on people health that were discovered later. This section of the paragraph needs to be revised as the fact people did not know about trans fats is not connected to the topic sentence that is the way popcorn become popular in the U.S., therefore, the best way to improve this paragraph is by "rewriting sentences that stray from the focus of the paragraph", that in this case are those that deal with the trans fats and are not related to the main idea of the paragraph.