Question

a solution containing equal numbers of hydrogen ions and hydroxide ions is acidic. alkaline. basic. neutral. in equilibrium.

Explanation:

In a solution, when the number of hydrogen ions ($H^+$) equals the number of hydroxide ions ($OH^-$), the pH is 7. A pH of 7 indicates a neutral solution. Acidic solutions have more $H^+$ ions, and basic/alkaline solutions have more $OH^-$ ions. Equilibrium is a more general state - here, the key is the neutral nature due to equal ion concentrations.

Answer:

D. neutral