The following data sufficiency problems consist of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you must indicate whether.
If q+r+s=45, what is the value of qr ？（）
(1) q=r=s
(2) q-r-s=-15
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
参考答案：A
解析：
alone is sufficient, because the only value for q, r, and s that meets the conditions of the question and the statement is 15; thus, we can determine the value of qr. (2) alone is not sufficient; although it would work for the values (q,r,s)=(15,15,15), it would also work for (q,r,s)=(15,14,16).