I will see you _____ Monday.

**The reasoning** English uses specific prepositions with time expressions, and days of the week always pair with **"on"**. Think of it like landing ON a specific day: - "I will see you **on Monday**" - "The meeting is **on Friday**" - "We travel **on weekends**" This is a fixed rule in English grammar called **preposition-time collocation**. Days are seen as specific points you land "on" in your weekly calendar. **Why the wrong options tempt you** **"In"** works for longer periods (in January, in 2024, in the morning) — but Monday is too specific, not a period. **"At"** works for clock times (at 3pm, at noon) or very specific locations in time (at Christmas) — but not days. **"Of"** never works with time expressions this way — it shows possession or relationship. **Quick takeaway** **On** the day, **in** the month/year, **at** the time — remember: you land ON specific days like stepping ON Monday's square on a calendar!