小白求助， 怎么看到不同答案。

The Excelworkbook QTR1.XLS contains the following three worksheets:
     JAN
     FEB
     MAR
Which statement correctly assigns a library reference to the Excel workbook?
     A. libname qtrdata ‘qtr1.xls’;
     B. libname ‘qtr1.xls’ sheets=3;
     C. libname jan feb mar ‘qtr1.xls’;
     D. libname mydata ‘qtr1.xls’WORK.heets=(jan,feb,mar);