Before a new contact lens cleaning solution can be sold, it must be tested on cultured human corneal cells to ensure it is safe to use.
Cultured corneal cells were placed into four identical culture wells. Sterile saline was added to the first well as a control, and a different brand of contact lens solution was added to each of the remaining three wells.
The corneal cells were incubated for 4 hours4\text{ hours}4 hours and the percentage of cells that remained healthy was recorded.
Table 1 shows the results.
Table 1
| Substance added to corneal cells | Percentage of healthy cells after 4 hours4\text{ hours}4 hours (%) |
|---|---|
| Sterile saline only | 92 |
| Lens solution Brand A | 91 |
| Lens solution Brand B | 93 |
| Lens solution Brand C | 92 |
Explain the conclusion that can be made from this data.
