Multi-choice problem: Choose from the options at the end, and answer how do you do this: to prevent your bathroom mirror from fogging up after a hot shower

Select from the following. -- after showering, run a bar of soap over the mirror lightly, making sure to cover the whole surface.; -- Before showering, run a bar of soap over the mirror lightly, making sure to cover the whole surface.;
Before showering, run a bar of soap over the mirror lightly, making sure to cover the whole surface.