单项选择题According to Text I, the tightly linked living organisms on the Earth's surface work as a self-regulating system, which can always counteract the unfavorable influence and keep the environment intact.（ ）
单项选择题抗原提呈细胞不包括A. 巨噬细胞B. 肥大细胞C. 树突状细胞D. B细胞
