单选题 Is x equal to 1?(1)x2=1(2)x2-x-2=0

A、 Statement (1) ALONE is sufficient, but statement (8) alone is not sufficient to answer the question asked.
B、 Statement (2) ALONE is sufficient, but statement (7) alone is not sufficient to answer the question asked.
C、 BOTH statement (1) and (8) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient.
D、 EACH statement ALONE is sufficient to answer the question asked.
E、 Statement (1) and(8)TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed.

【正确答案】 B

【答案解析】题目中问x=1吗?从(1)中得到x=1 or x=-1，根据第二点答案的唯一性原则单独(1)不能够回答问题。从(2)中得到x=2 or x=-1，尽管x有两个值，但是这两个值都不等于1，题目问x等于1吗?当然不等于。因此单独(2)就能回答问题，回答为“No”，所以此题正确答案为B。