One Mole of a Liquid Is Vaporized at Its Boiling $\Delta$

One mole of a liquid is vaporized at its boiling point, 65°C and 1.00 atm. $\Delta$ H_vap for the liquid is 43.8 kJ/mol at 65° C.
-Calculate w.

A) -27.7 J
B) 27.7 J
C) 2.81 * 10³ J
D) -2.81 * 10³ J
E) none of these