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: Brain cells die quickly if their oxygen supply is cut off., Fact2: Astroglial cells are the most common cells in brain tissue., Question: what dies is their oxygen supply is cut off? (A) trees (B) Plant growth is reduced (C) weathering (D) Veins and arteries. (E) Most plants (F) astroglial cells (G) critical organs (H) gravity
F