Chemistry - GOC Question with Solution | TestHub

$-\mathrm{O}{\mathrm{C}}_2{\mathrm{H}}_5$ (O is more electronegative than the ring carbon), $-\mathrm{C}\equiv \mathrm{N}$ (sp carbon, N) and $-\mathrm{C}{\mathrm{F}}_3$ (three F atoms) all pull electrons from the ring (-I).

In $-\mathrm{CH}(\mathrm{C}{\mathrm{H}}_3{)}_2$ the $\mathrm{s}{\mathrm{p}}^3$ carbon is less electronegative than the $\mathrm{s}{\mathrm{p}}^2$ ring carbon, so the alkyl group pushes electrons to the ring: +I.