答案选C,这里that是关系代词,引导定语从句,引导定语从句的关系代词有that（指代人或物）、which（指代物）、who（指代人）,题中先行词the tall man是人,所以用只有that可选.the tall man that/who wears a new coat意思是穿着一件新衣服的高个男子.Awhat是疑问代词,可以引导主语从句或宾语从句,而whose要和后面的名词构成从属关系,如the tall man whose car is blue is our teacher.