Two $100.0\mathrm{mL}$ portions of a hard water are analysed with $0.0100\mathrm{M}$ EDTA (EBT, pH 10). The first (raw water) needs $17.5\mathrm{mL}$. The second is boiled, filtered and made up again to $100.0\mathrm{mL}$, and needs $6.8\mathrm{mL}$. Taking $\mathrm{CaCO}{}_3=100$, the temporary hardness in ppm of $\mathrm{CaCO}{}_3$ is:

1. A$68$
2. B$107$
3. C$243$
4. D$175$