Why A over B?

@Lucie Happy to help! (A) states "No student who completes anything less than all of the reading assignments for a course will earn a high grade for that course." In other words, (A) is saying that all students who do not complete every reading assignment will not earn a high grade. This can be diagrammed as: not CR -> not HG. The contrapositive of this is: HG -> CR. (B) states "Any student who completes all of the reading and written assignments for a course will earn a high grade in that course." In other words, (B) is saying that all students who complete every reading and writing assignment will earn a high grade. This can be diagrammed as: CRW -> HG. The contrapositive of this is: not HG -> not CRW. Note that (B) includes written assignments and (A) does not. Moreover, in (A) a student who completes all of the reading assignments is not guaranteed to earn a high grade, whereas that same student in (B), assuming they also completed all written assignments, would be guaranteed a high grade. In (B) a student who does not complete all reading and written assignments may still earn a high grade, whereas that student would not in (A). Does that make sense? Please let us know if you have any other questions!