A student studied the rate of photosynthesis in four plant species at $20\,^{\circ}\mathrm{C}$ and at $30\,^{\circ}\mathrm{C}$. Every other condition was kept unchanged. Which statement is a valid conclusion drawn from these data?
- ASpecies W photosynthesises at a lower rate at $20\,^{\circ}\mathrm{C}$ than at $30\,^{\circ}\mathrm{C}$.
- BSpecies X has the greatest change in rate of photosynthesis between $20\,^{\circ}\mathrm{C}$ and $30\,^{\circ}\mathrm{C}$.
- CSpecies Y photosynthesises at the highest rate at both $20\,^{\circ}\mathrm{C}$ and $30\,^{\circ}\mathrm{C}$.
- DSpecies Z photosynthesises at the highest rate at $20\,^{\circ}\mathrm{C}$ and the lowest rate at $30\,^{\circ}\mathrm{C}$.