In the anion $HCOO^-$ the two carbon-oxygen bonds are found to be of equal length. What is the reason for it ?

Question

( A ) The $C=O$ bond is weaker than the $C-O$ bond
( B ) The anion $HCOO^-$ has two resonating structures
( C ) Electronic orbits of carbon atom are hybridised
( D ) The anion is obtained by removal of a proton from the acid molecule