94. Given the following SAS error log
44 data WORK.OUTPUT;
45 set SASHELP.CLASS;
46 BMI=(Weight*703)/Height**2;
47 where bmi ge 20;
ERROR: Variable bmi is not on file SASHELP.CLASS.
48 run;
What change to the program will correct the error?
A.Replace the WHERE statement with an IF statement
B. Change the ** in the BMI formula to a single *
C. Change bmi to BMI in the WHERE statement
D.Add a (Keep=BMI) option to the SET statement
Answer: A

为什么不能用C呢？ 虽然选对了，但还是不是特别清楚。
谢谢！