Min-Ahn spends 1.5 hours creating a 35-slide PowerPoint presentation for his POM class, while Ying takes only 45 minutes to prepare his 28- slide presentation. Which of the following is correct?
a) Min-Ahn's productivity is 0.39
b) Ying's productivity is 37.33
c) Ying's productivity is 0.622
d) All of the above