Final answer:
Student B read 0.2 books per week.
Step-by-step explanation:
To determine which student read 0.2 books per week, we need to divide the number of books each student read by the 40-week school year. Let's calculate:
Student A: 4 books / 40 weeks = 0.1 books per week
Student B: 8 books / 40 weeks = 0.2 books per week
Student C: 2 books / 40 weeks = 0.05 books per week
Student D: 5 books / 40 weeks = 0.125 books per week
Therefore, Student B read 0.2 books per week.