Use the following rule set. Slater's rules: write the configuration in groups $(1s)(2s,2p)(3s,3p)(3d)(4s,4p)(4d)(4f)(5s,5p)\dots$ For an electron in an $ns$ or $np$ group, every other electron in the same group contributes $0.35$ ($0.30$ for the $1s$ group), every electron in the $(n-1)$ shell contributes $0.85$, every electron in the $(n-2)$ or lower shells contributes $1.00$, and electrons in groups to the right contribute $0$. For an electron in an $nd$ or $nf$ group, every other electron in the same group contributes $0.35$, every electron in all groups to its left contributes $1.00$, and groups to the right contribute $0$. $Z^{\ast }=Z-S$. The ions $\mathrm{K}{}^{+}$ and $\mathrm{Cl}{}^{-}$ are both $(1s{)}^2(2s,2p{)}^8(3s,3p{)}^8$. The Slater $Z^{\ast }$ values for a $3p$ electron of $\mathrm{K}{}^{+}$ and $\mathrm{Cl}{}^{-}$ respectively are:

1. A5.75 and 7.75
2. B7.75 and 5.75
3. C7.40 and 5.40
4. D11.00 and 9.00