Chemistry - GOC Question with Solution | TestHub

$\mathrm{C}{\mathrm{H}}_3$ donates by +I and hyperconjugation. $\mathrm{C}{\mathrm{D}}_3$ is a slightly weaker donor than $\mathrm{C}{\mathrm{H}}_3$ because C-D is a poorer σ donor, so (b) is below (a) but still above the plain benzyl cation (c). $\mathrm{C}{\mathrm{F}}_3$ withdraws by -I and is the least stable (d).

Order : a $>$ b $>$ c $>$ d.