Correct Answer - B
Arenediazonium salts react with hypophosphorus acid `(H_(3)PO_(2))` to yield products in which diazonium salt has been replaced by `-H`
`ArN_(2)+Cl^(bar)+H_(3)PO_(2)+H_(2)OrarrArH+N_(2)+H_(3)PO_(3)+HCI`
During this process hypophosphorus acid is oxidized to phosphoric acid `(H_(3)PO_(3))` .