A study compared reading scores at four schools that varied in average daily attendance (high/low) and homework hours per week (low/high): School A, high attendance + low homework, 78; School B, high attendance + high homework, 86; School C, low attendance + low homework, 64; School D, low attendance + high homework, 72. The researchers argued that homework hours independently boost scores even after controlling for attendance. The strongest data support is ______
Which choice most logically completes the text using the data above?
- A
the comparison A vs. C.
- Bcheck_circle
the comparison A vs. B (both high attendance: 78 → 86) and C vs. D (both low attendance: 64 → 72)—homework adds about 8 points in each pair.
- C
School C's score of 64.
- D
School B's score of 86.
Explanation
To argue homework's independent effect, you compare schools with the same attendance but different homework levels. Choice C does this in both the high- and low-attendance subgroups, showing homework adds a similar boost regardless of attendance.