Explanation:

Let’s break it down:

- Mere words: Just saying something threatening doesn’t amount to assault. There must be an act or gesture giving the victim a reasonable fear of immediate harm.

- Mere gestures: These alone, if they create reasonable apprehension of harm (like raising a fist), can amount to assault—even if no physical contact happens.

- Mere preparation: Getting ready to do something (like buying a knife, but not actually threatening with it) isn’t assault. There’s no immediate threat or act.

- None: This would mean all of the above could cause assault, which just isn’t true.

Here’s the catch: Assault cannot be caused by mere preparation.

- If someone just prepares but doesn't actually do anything to make another person fear immediate harm, it’s not assault.

So the correct answer is:

Option: 3, Mere preparation