The following SAS program is submitted:
proc freq data = sales;
<insert TABLES statement here>
A00-211
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run;
Click the Exhibit button to view the output from the FREQ procedure.
Which one of the following statements completes the program and produces
the output?
A. tables region product;
B. tables region * product;
C. tables product region;
D. tables product * region;
Answer: B

C 为何不对呢？c可以解释为只对variables products and region做分析。错的原因在哪呢？