Final answer:
In a graph representing a hypertonic solution and its effects on a paramecium, the x-axis would typically contain the salt concentration outside of the cell, showing various levels of extracellular solute concentration and allowing for the observation of the cell's response. The correct option is a.
Step-by-step explanation:
When dealing with a hypertonic solution, the information that belongs on the x-axis would typically be the salt concentration outside of the paramecium. This is because the hypertonic solution refers to the extracellular fluid having a higher solute concentration than the cell's cytoplasm, resulting in water exiting the cell.
In order to graph the relationship between the environment's salt concentration and the cellular response, you would plot various concentrations of salt on the x-axis and observe the corresponding cellular behavior, such as rate of contractions per minute, along the y-axis. In the case of a paramecium, which likely refers to a lab experiment observing the impact of different salinities on paramecium contraction rate, this would show how paramecium behave in different osmolarity conditions, demonstrating cell's activity under different levels of external solute concentration.
Thus, the x-axis could show a range of salt concentrations increasing from left to right (like 'Low', 'Medium', 'High'), correlating with the different hypertonic solution conditions that the cell might be placed in.
Hence, Option a is correct.