The Boiling Point of a Solution of NaOH in H₂O

The boiling point of a solution of NaOH in H₂O is 100.84°C. What is the molality of the solution? Assume that NaOH is not volatile. (K_b = 0.51200°C/m for H₂O₄; T_BP = 100.00°C) .

A) 1.112 m
B) 1.857 m
C) 1.641m
D) 0.9568 m
E) 0.8205 m