A circular disc has a measured diameter of $(7.0 \pm 0.1)\,\text{mm}$. Determine its area and the absolute uncertainty in the area.
- Aarea of disc $= 38.5\,\text{mm}^2$, absolute uncertainty $= \pm 0.5\,\text{mm}^2$
- Barea of disc $= 38\,\text{mm}^2$, absolute uncertainty $= \pm 1\,\text{mm}^2$
- Carea of disc $= 154\,\text{mm}^2$, absolute uncertainty $= \pm 2\,\text{mm}^2$
- Darea of disc $= 154\,\text{mm}^2$, absolute uncertainty $= \pm 4\,\text{mm}^2$