Cyclohepta-1,3,5-triene reacts with triphenylmethyl cation, $(\mathrm{C}{}_6\mathrm{H}{}_5){}_3\mathrm{C}{}^{+}$, by transfer of a hydride ion from its $\mathrm{CH}{}_2$ group to give $\mathrm{C}{}_7\mathrm{H}{}_7{}^{+}$ and triphenylmethane. The main reason this hydride transfer is favourable is that:

1. A$\mathrm{C}{}_7\mathrm{H}{}_7{}^{+}$ is cyclic, planar and fully conjugated with 6 pi electrons, i.e. aromatic
2. B$\mathrm{C}{}_7\mathrm{H}{}_7{}^{+}$ has 8 pi electrons and is therefore antiaromatic and stable
3. C$\mathrm{C}{}_7\mathrm{H}{}_7{}^{+}$ is a tertiary carbocation with many alpha hydrogens
4. DThe C-H bond of the $\mathrm{CH}{}_2$ group of the triene is unusually weak because it is sp hybridised