Error, ignoring CaCO3 precipitation. C error, ignoring BaSO4 precipitation.

B controversial. Change the topic to sulfur dioxide into sodium hypochlorite solution containing NaOH, and there will be no dispute.

It is generally believed that sulfur dioxide is introduced into sodium hypochlorite solution,

ClO- + SO2 + H2O = Cl- + SO42- + 2 H+

SO2 + NaClO + H2O= H2SO4+NaCl

Don't pay too much attention to this poor problem.

If you only choose D, you will get half a point.