The Freezing Point of Pure Benzene Was Measured as 5

The freezing point of pure benzene was measured as 5.49°C. With the same benzene and same equipment, the freezing point of a solution containing 6.582 g of an unknown molecular compound (sold in the store as "moth crystals") in 100.203 grams of benzene was found to be 3.48°C. The cryoscopic constant, Kf, for benzene is 5.12 deg-kg/mole. Calculate the mole weight of the unknown.

A) 37.5 g/mol
B) 16.7 g/mol
C) 96.6 g/mol
D) 70.4 g/mol
E) 167 g/mol