The experimental dipole moments are about $2.2\mathrm{D}$ for cyclohexyl chloride and $1.7\mathrm{D}$ for chlorobenzene. The best explanation of the lower value for chlorobenzene is that

1. Achlorine is less electronegative when attached to a benzene ring
2. Bthe ring $s{p}^2$ carbon is more electron-attracting than an $s{p}^3$ carbon and chlorine donates electrons into the ring by resonance, so the C-Cl bond is less polar
3. Cthe C-Cl bond in chlorobenzene is longer than in cyclohexyl chloride
4. Dthe pi cloud of the ring carries an equal and opposite dipole that exactly cancels part of the moment