The correct increasing order of the basic strength for the following compounds is:

• A

  $\mathrm{II}<\mathrm{III}<\mathrm{I}$
• B

  $\mathrm{III}<\mathrm{I}<\mathrm{II}$
• C

  $\mathrm{III}<\mathrm{II}<\mathrm{I}$
• Correct answer
  D

  $\mathrm{II}<\mathrm{I}<\mathrm{III}$

Solution

$-{\mathrm{NO}}_2$ has a strong $–\mathrm{M}$ effect and $-{\mathrm{CH}}_3$ shows $+\mathrm{I}, \mathrm{HC}$ effect,

Basic strength $\propto +\mathrm{M},+\mathrm{I},\mathrm{HC}$

$\therefore$ Order of basic strength is:

Hence, the correct answer is option: 'D'.