$\mathop {Ph - OH}\limits_{(A)} ,\,\,\,\,\mathop {Ph - C{H_2} - OH}\limits_{(B)} ,\,\,\,\,\mathop {Ph - C{O_2}H}\limits_{(C)} ,\,\,\,\mathop {Ph - C{H_2}-\mathop N\limits^ \oplus {H_3}}\limits_{(D)} $
$a$ અને $b$ વચ્ચે ની બંધ લંબાઈ નો સાચો ક્રમ કયો છે ?


${ }^{-} \mathrm{OH}, \mathrm{R} \overline{\mathrm{O}}, \mathrm{CH}_3 \mathrm{CO} \overline{\mathrm{O}}, \mathrm{C} \overline{1}$