Which of the following series of compounds have the same mass percentage of carbon?

(d) $\frac{12}{30}\times 100,\frac{24}{60}\times 100,\frac{72}{180}\times 100$

The compounds have the same mass percentage of carbon is $\mathrm{HCHO},{\mathrm{CH}}_3\mathrm{COOH},{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$.