If a 239.86 mg sample yielded 646.95 mg of carbon dioxide and 264.89 mg of water in a combustion analysis, what is the percentage composition of carbon and hydrogen in the unknown sample?
a) Carbon: 63.7%, Hydrogen: 26.9%
b) Carbon: 72.7%, Hydrogen: 29.7%
c) Carbon: 58.7%, Hydrogen: 21.9%
d) Carbon: 70.7%, Hydrogen: 34.9%