Definition: 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").
Input: Fact1: adding salt to a solid decreases the freezing point of that solid, Fact2: Another name for salt is sodium., Question: What can you add to a solid to lower its freezing point? (A) calcite (B) energy (C) heat (D) sodium (E) boiling (F) Solutions (G) salinity (H) Energy.
Output:
D