The anode half-reaction occurring during the discharge of a lead storage battery is

• A
  $Pb(s)+SO_4{ }^{2-}(aq) \rightarrow PbSO_4(s)+2 e^{-}$
  
   
• B
  $PbO_2(s)+4 H^{+}(aq)+SO_4{ }^{2-}(aq)+2 e^{-} \rightarrow PbSO_4(s)+2 H_2 O(l)$
• C
  $Pb^{2+}(aq)+SO_4{ }^{2-}(aq) \rightarrow PbSO_4(s)$
• D
  $Pb(s)+SO_2+O_2 \rightarrow PbSO_4(s)$