Given the task definition and input, reply with output. 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: when electricity flows to a light bulb , the light bulb will turn on, Fact2: Materials that control the flow of electricity are called resistors., Question: What could prevent a light bult from turning on? (A) sensory neurons (B) herbicide (C) A resistor (D) focusing a lens (E) evaporation (F) heat energy (G) heating liquids (H) energy barrier
C