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: Viruses are so small that they can be seen only with an electron microscope., Fact2: Viruses include the Tobacco Mosaic Virus., Question: How can cells of the Tobacco Mosaic be seen? (A) refraction of light (B) an area swollen with pus (C) by indirect light (D) death and devastation (E) bending light rays (F) electron microscope (G) deadly and devastating (H) Veins and arteries.
F