The correct option is D All of the above
Let, the oxidation number of C be x
We know that,
Oxidation number of H=+1
Oxidation number of Cl=−1
Oxidation number of O=−2
(A) HCHO
+1+x+1+(−2)=0
x=0
(B) CH2Cl2
x+(2×1)+(2×−1)=0
x=0
(C) C6H12O6
6x+(1×12)+(−2×6)=0
x=0
Hence, Carbon is in zero oxidation state in all the given compounds.