Chris has a painful knee injury, and is told by physician to take his pain-relieving medication whenever the pain becomes intolerable. After several days of taking the medication as needed, Chris notices that he has to take two tablets for pain relief where before one had been enough. Chris is probably
(A) addicted to the drug.
(B) becoming psychologically dependent on the drug.
(C) developing a tolerance for the drug.
(D) showing withdrawal symtoms from the drug.
Chris的膝蓋受了嚴重的傷，醫生告訴他，當疼痛難以忍受時就服用止痛藥。Chris按需服藥幾天後，他發現現在必須服用兩個藥才能止痛，而之前只需要一片。Chris 很可能是
(A) 對藥物上癮了
(B) 開始對藥物產生心理依賴
(C) 對藥物產生了耐受性
(D) 出現了戒斷症狀
