Oxygen symbol.

**The reasoning** In chemistry, every element has a **unique chemical symbol** — a shorthand way to represent it. These symbols are internationally agreed upon and found on the Periodic Table. Oxygen's symbol is simply **O** (capital letter). It comes from the first letter of its English name. This is standard notation used worldwide in chemical formulas like H₂O (water) or CO₂ (carbon dioxide). **Why the wrong options tempt you** - **B) Ox** — You might think "Ox" sounds like "oxygen," but chemical symbols are never two letters where the second is 'x' for oxygen. "Ox" isn't chemistry; it's a farm animal! - **C) Oy** — Similar confusion. No element uses 'y' after 'O' like this. - **D) Oxy** — This appears in words like "oxy-acetylene" or "oxygenated," but it's a *prefix*, not the chemical symbol. The trap here is overthinking. Students sometimes expect symbols to match how words *sound* rather than following the strict Periodic Table convention. **Quick takeaway** Oxygen is always **O** — one capital letter, straight from the Periodic Table; anything longer is not a chemical symbol.