In singlet methylene, $\text{:}\mathrm{CH}{}_2$, the carbon atom is best described as

1. A$sp$ hybridised with two unpaired electrons in $p$ orbitals
2. B$s{p}^3$ hybridised with two lone pairs
3. C$s{p}^2$ hybridised with a filled $p$ orbital and an empty $s{p}^2$ orbital
4. D$s{p}^2$ hybridised, with a lone pair in one $s{p}^2$ orbital and an empty $p$ orbital