Answer: A. The higher the pH is, the more the hydroxide ion concentration decreases and the more acidic the solution becomes.
Basic solutions are solutions with pH higher than 7 while acidic solutions are solutions with pH lower than 7. On the pH scale, the value from 0 to 6.9 indicates that the solution is an acidic one while the value from 7.1 to 14 indicates that the solution is a basic one. With this, a higher pH means a more basic solution. A base is known to dissociate in an aqueous solution to form Hydroxide ions. A higher pH, therefore, means more concentration of Hydroxide ion and therefore, a more basic solution.