Two polystyryl radicals, each ending in $- CH X_{2} - CH (C X_{6} H X_{5})$ with the unpaired electron on the carbon bearing the phenyl group, terminate by disproportionation. The products are

Atwo dead chains, both ending in $- CH = CH - C X_{6} H X_{5}$
Btwo dead chains, one ending in $- CH X_{2} - CH X_{2} - C X_{6} H X_{5}$ and the other in $- CH = CH - C X_{6} H X_{5}$
Ctwo dead chains, both ending in $- CH X_{2} - CH X_{2} - C X_{6} H X_{5}$
Done dead chain joined through a new $C - C$ bond between the two radical carbons

Answer: B

In disproportionation one radical abstracts a hydrogen atom from the

CH X_{2}

next to the radical centre of the other. The abstracting chain becomes saturated (

- CH X_{2} - CH X_{2} - C X_{6} H X_{5}

) and the donor becomes unsaturated (

- CH = CH - C X_{6} H X_{5}

). Two chains result, unlike combination, which gives one.