A study compared math achievement at four schools differing in two ways: tracking policy (yes/no) and average teacher experience (low/high). Scores: School J, tracked + low experience, 65; K, tracked + high experience, 78; L, untracked + low experience, 64; M, untracked + high experience, 79. The researchers concluded that tracking has essentially no effect on math achievement once teacher experience is controlled. The strongest data support is ______
Which choice most logically completes the text using the data above?
- A
the gap between J and M.
- Bcheck_circle
the close match within experience strata: J vs. L (65 vs. 64) and K vs. M (78 vs. 79)—tracking changes scores by only 1 point.
- C
School M's score of 79.
- D
School J's score of 65.
Explanation
"Tracking has essentially no effect once experience is controlled" requires showing that holding experience constant and varying tracking produces tiny score differences. Choice B does this in both experience strata.