Question

which of these do bases release in water? hydroxide ions (oh-) hydrogen ions (h+)

Explanation:

In chemistry, bases are substances that, when dissolved in water, release hydroxide ions ($\text{OH}^-$). Acids, on the other hand, release hydrogen ions ($\text{H}^+$) in water. So bases release hydroxide ions ($\text{OH}^-$) in water.

Answer:

hydroxide ions (OH-)