第11题: [单项选择]In paragraph 3, "such a reaction" refers back to ______. A. asking a choice between "flight or fight" B. "reaction to stress both chemically and physically" C. "responding to crises quickly" D. "losing heart at the signs of difficulties" 参考答案:B 答案解析:推理题。根据上下文大意可知,这种反应是指在压力面前人体产生的物理和化学反应。