Answer the following question given this paragraph: 

Hydroxides Hydroxides are compounds that contain the OH− ion. It is possible to prepare these compounds by two general types of reactions. Soluble metal hydroxides can be produced by the reaction of the metal or metal oxide with water.


Q: What is produced by the reaction of metal oxide with water?

 Choices:

- heat energy

- rust

- hydrogen gas

- soluble metal hydroxides

A:
soluble metal hydroxides
