Title: Bob Learns a Lesson. Sentence 1: Bob found pool maintenance to be a tiresome chore. Sentence 2: He had to add chlorine every week. Sentence 3: He wondered how a salt pool could stay clean without chlorine. Sentence 4: He learned that the engine of the salt pool separated elements. Choices: a. But after several months, she didn't improve. b. Of course, he understood because salt is sodium and chlorine.
b