Sodium salt of an organic acid 'X' produces effervescence with conc. $H_2SO_4$. 'X' reacts with the acidified aqueous $CaCl_2$ solution to give a white precipitate which decolourises acidic solution of $KMnO_4$. 'X' is :

Question

( A ) $CH_3COONa$
( B ) $HCOONa$
( C ) $C_6H_5COONa$
( D ) $Na_2C_2O_4$