Which of the following organic compounds contains about 52% carbon ?

Molar mass of dimethyl ether = $(2\times 12 + 6\times 1 + 1\times 16) = 46 \mathrm{g} {\mathrm{mol}}^{-1}$
We have, mass of carbon in 1 mole of dimethyl ether = $12\times 2 = 24 \mathrm{g} {\mathrm{mol}}^{-1}$
Therefore, percentage of carbon = $\frac{24}{46}\times 100$ % = 52.17 % = 52% (approx)