The correct answer is 1 isotonic.
Isotonic solutions refer to two solutions that have the same concentration of solute, meaning that the percentage of solute and solvent is equal in both. This is particularly important in biological contexts where cells exist in various osmotic environments. When two isotonic solutions are in contact, there is no net movement of water across a semipermeable membrane, leading to equilibrium. In contrast, hypotonic solutions have a lower concentration of solute compared to another solution, while hypertonic solutions have a higher concentration. Non-potable refers to water that is unsafe for drinking rather than a property of solutions. Thus, isotonic is the appropriate term to describe solutions with identical solute and solvent percentages.