单选题 A certain mathematical operation may be represented by the symbol@. For all nonzero a and b, does a@b=b@a?(1)m@n=1/2, for all nonzero m.(2)a@6=ab/(a2+b2), for all nonzero a and b.

A、 Statement (1) ALONE is sufficient, but statement (34) alone is not sufficient to answer the question asked.
B、 Statement (2) ALONE is sufficient, but statement (33) alone is not sufficient to answer the question asked.
C、 BOTH statement (1) and (34) 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(34)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】单独Statement (1)，由m@m=1/2只能得到a@a=1/2，b@b=1/2，但是a@b怎么样无法求得。单独Statement (2)，a@b=ab/(a2+b2)，b@a=ba/(b2+a2)，得到a@b=b@a，因此B为正确答案。