In the chemical reactions given above \( A \) and \( B \) respectively.
\( \mathrm{H_3PO_2} \) and \( \mathrm{CH_3CH_2OH} \)
\( \mathrm{CH_3CH_2OH} \) and \( \mathrm{H_3PO_2} \)
\( \mathrm{H_3PO_2} \) and \( \mathrm{CH_3CH_2Cl} \)
\( \mathrm{CH_3CH_2Cl} \) and \( \mathrm{H_3PO_2} \)