Which of the following reactions is taking place resulting in discolouration of marble of the buildings like Taj Mahal?
A. ` CaCO_(3) +H_(2) SO_(4) to Ca SO_(4) +H_(2) O +CO_(2)`
B. `CaCO_(3) +2HCl to CaCl_(2) + H_(2)O+CO_(2)`
C. ` CaCO_(3) +H_(2)O to Ca(OH)_(2) +CO_(2)`
D. ` CaCO_(3) to CaO +CO_(2)`