The study looked at how acid rain affects the photosynthesis and chlorophyll levels of Quercus glauca seedlings. They exposed the seedlings to acid rain with different pH levels and found that lower pH levels of acid rain actually increased the seedlings' photosynthesis. Seedlings exposed to pH 2.5 and 4.0 had higher photosynthetic rates and chlorophyll levels compared to those exposed to pH 5.6. This suggests that acid rain with pH 2.5 and 4.0 can improve the growth of Quercus glauca seedlings.