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: All chemical reactions require activation energy to get started., Fact2: Chemical changes are a result of chemical reactions., Question: What do ALL chemical changes require to occur? (A) during the day (B) heating liquids (C) Activation energy (D) wavelengths and photons (E) Burning fuel and air (F) kinetic energy (G) electromagnetic energy (H) direct energy
Output:
C