Choose the option opposite in meaning to the word or phrase underlined. Before going to bed, make sure you extinguish all the lights.

The word "extinguish" typically refers to the act of putting out something like a fire, or in this case, turning off lights. When we search for the opposite meaning, we are looking for a word or phrase that conveys the idea of activating or starting something.

Analyzing the options provided:

1. "Turn off" means to deactivate or stop something from functioning. This does not represent the opposite of extinguishing, as they both suggest a stopping action.

2. "Turn out" is more commonly used for lights meaning to extinguish or turn off, similar to "extinguish."

3. "Switch on" refers to activating or starting something, like turning on a light. This is the opposite of "extinguish."

4. "Switch off" is similar in meaning to "extinguish," as it suggests stopping or deactivating lights or electrical devices.

Thus, the option that is opposite in meaning to "extinguish" is "switch on", as it involves starting or turning on something instead of stopping it.