Teacher: In this task, you will be presented with a question having multiple possible answers in Chinese language. And you should choose a most suitable option out of "A", "B", "C", "D", and "E" based on your commonsense knowledge.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Question: 牙科诊所处理了很多口外伤的患者，这些患者来自哪里？ 
 Options: (A) 城镇 (B) 密西根 (C) 办公楼 (D) 医院 (E) 学校 
Solution: D
Reason: This is the correct answer because the traumatic injuries are generally handled by the hospitals.

Now, solve this instance: Question: 丹喜欢下棋，但他就是下不了了。  他被什么削弱了？ 
 Options: A 无聊 B 谦逊 C 头痛 D 挫折 E 关节炎 
Student:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
C