Area of a circle radius 5 (π).

**The reasoning** The formula for the area of a circle is **A = πr²** (pi times radius squared). Here, radius r = 5, so: - A = π × (5)² - A = π × 25 - A = **25π** The key word is "squared" — you must multiply the radius by itself first, *then* multiply by π. **Why the wrong options tempt you** - **A) 5π** — You forgot to square! You just wrote πr instead of πr². This is the most common mistake. - **B) 10π** — You multiplied the radius by 2 first (thinking of diameter or circumference formula C = 2πr), then added π. Wrong formula entirely. - **D) 50π** — You multiplied 5 × 10 somehow, maybe confusing diameter (10) with radius. **Quick takeaway** **Area needs squaring: A = πr².** Circumference is the one with "2" in front (C = 2πr). Never mix them up — area grows with the *square* of the radius, so small changes in radius mean BIG changes in area!