The data in the graph are the result of a paramecium being placed in a hypertonic salt solution.

A graph entitled Paramecium Contractile Vacuole Contractions has salt concentration on the horizontal axis and contractions per minute on the vertical axis. A very low salt concentration has 30 contractions per minute, low: 22, medium: 15, high: 8, very-high: 2.

What change would most improve the usefulness of the graph?
Replace the concentration descriptions with actual values.
Plot contractions per second instead of contractions per minute.
Remove the plotted points and just keep the line.
Remove the name of the organism from the title.