In diffusion, molecules of a substance move from areas of concentration to an area of concentration. Plz help and I need an answer very soon THANKS YALL

Answer asap 50 points which of the following distinguishes the soil composition of grassland? 1. the soil supports large trees with thick, long roots, so horizon b needs to be deep enough to sustain larger flora. 2. the soil supports large trees with thick, long roots, so horizon a needs to be deep enough to sustain larger flora. 3. the soil supports small plants and shrubs with short roots, so horizon a needs to be deep enough to sustain smaller flora. 4. the soil supports small plants and shrubs with short roots, so horizon b needs to be deep enough to sustain smaller flora.