An organic compound contains $8$% oxygen and $4$% sulphur by mass. The minimum possible molecular weight of the compound is:

The correct option is C $800$
For every $100$ g of the organic compound, $8$ g of $O$ and $4$ g of $S$ are present.

The atomic weights of oxygen and sulphur are $16$ g/mol and $32$ g/mol respectively.

The molecule should contain at least one $O$ atom and one $S$ atom.

The minimum possible molecular weight of compound is $\frac{32}{4}\times 100=800$ g/mol.

Hence, the correct option is $C$