When you're signing up for next semester's classes, you might opt for another history class, or instead opt for advanced biology. [выбирать]

If you're dealing with confinement to a jail cell, or your room, you're stuck there and you can't leave. Confinement means you're being held and you can't move freely. [заточение]

Feeling elated is all about being so extremely proud and overjoyed, and usually happens as a result of an accomplishment. So if you've just achieved something big, feel free to be elated — and enjoy your time on cloud nine. [ликующий, окрыленный]

The word watchdog [наблюдатель] has another meaning: a dog trained to guard property [сторожевая собака]. Remember, everyone is watching you.