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: Differentiation is the process by which unspecialized cells become specialized., Fact2: Nerve cells are large, complicated, highly specialized cells., Question: What is essential for development of nerve cells? (A) vibration (B) steel (C) Extensive bone growth (D) One can hear (E) stress (F) melanin content (G) sound vibrations (H) differentiation
H