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: a seismograph is used for measuring the size of an earthquake, Fact2: Richter magnitude is a measure of the size of the earthquake., Question: what is a seismograph used for measuring? (A) Differences in speed (B) hurricane speed (C) occurs over a wide range (D) Major effects (E) eruptive products (F) Richter magnitude (G) 70-75 degrees Fahrenheit (H) vertebrae or backbone
Output:
F