An experiment was used to determine the rate at which plants absorb magnesium ions from solution. One plant was treated with a poison that prevents respiration, whereas another plant was left untreated. The graph shows the results. By what process are the magnesium ions being taken up by the plants at points N and P?
- Apoint N: active transport, point P: active transport
- Bpoint N: active transport, point P: diffusion
- Cpoint N: diffusion, point P: active transport
- Dpoint N: diffusion, point P: diffusion