You will be given a definition of a task first, then some input of the task.
In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").

Fact1: heating salt water causes the water to evaporate while the salt remains, Fact2: Evaporation of the water leaves the salt on the surface., Question: heating salt water leaves the salt where? (A) solid, liquid, gas (B) on the surface (C) Solutions (D) epidermis and dermis (E) lowered energy cost (F) energy barrier (G) an object (H) near the shoreline
Output:
B