The correct option is B 2
Calcium hydroxide = Ca(OH)2
Each OH− ion has one net negative charge as oxygen has a valency of -2 and hydrogen has a valency of +1.
Now, as calcium hydroxide is a neutral compound, so it is possible only when calcium has a net positive charge of +2.
So, the valency of calcium in Ca(OH)2 is 2.
Also, Ca(OH)2 → Ca2++2OH−