What provides hydroxide ions (OH-) or other negatively charged ions to a solution?

Bases are substances that, when dissolved in water, dissociate to produce hydroxide ions (OH-) or other negatively charged ions. This process typically increases the concentration of OH- in the solution, making it more alkaline or basic.

In the context of pH, bases have a pH greater than 7, which indicates a higher concentration of hydroxide ions compared to hydrogen ions (H+). This is fundamental to understanding acid-base chemistry, where acids produce hydrogen ions in solution, while bases provide hydroxide ions.

Other options do not generate hydroxide ions. Acids, for instance, release H+ ions and are characterized by a pH lower than 7. Salts can dissociate into cations and anions in solution, but they do not necessarily provide hydroxide ions unless they are formed from a reaction involving a base. Neutral solutions have an equal concentration of H+ and OH- ions, resulting in a balanced pH of 7. Therefore, the defining characteristic of bases in this context is their ability to contribute hydroxide ions to a solution, aligning with the correct answer.