Answer: 7 cases
Given:
Riva crafts and sells hard cider as a part-time job.
Riva sells four cases in a week.
Case: If she hires Atul
Atul can bottle and sell three cases per week.
Therefore in this particular case the the maximum total output possible if Riva hires Atul will be 7 cases .
Therefore, the correct option is (b).