Supply the major carbon containing products 'A' and 'B' in the following reaction.

• A

  $\mathrm{A}\to {\mathrm{CH}}_3-{\mathrm{CH}}_2\mathrm{COOH}; \mathrm{B}\to \mathrm{HCOOH}$

• B

  

• C

  $\mathrm{A}\to {\mathrm{CH}}_3-\mathrm{COOH}; \mathrm{B}\to {\mathrm{CH}}_3\mathrm{COOH}$

• D