题目内容：
根据资料回答第题。
When a consumer finds that his purchase has a fault in it, the first thing he should do is to__________．
A. complain personally to the manager
B. threaten to take the matter to court
C. write a firm letter of complaint to the store of purchase
D. show some written proof of the purchase to the store
参考答案：
答案解析：