A spring is hung from a fixed support, and a force is then exerted on it. The reading of a pointer attached to the lower end of the spring is noted using a vertical ruler. Before any force is exerted, the pointer reads $(225 \pm 2)\,\text{mm}$. Once the force has been exerted, the pointer reads $(250 \pm 2)\,\text{mm}$. The spring’s extension is found. What is the percentage uncertainty in the extension?
- A$1.6\%$
- B$1.8\%$
- C$8.0\%$
- D$16\%$