请问 SAS Base 70题库中 的  第29题，到底是 选 A 还是 B?题目复制如下

29.The following SAS program is sumbitted:
 
  

data WORK.INFO;
     
    infile ‘DATAFILE.TXT’;
     
    input @1 Company $20. @25 State $2. @;
     
    if State=’ ‘ then input @30 Year;
     
    else input @30 City Year;
     
    input NumEmployees;
  
run;
 


How many raw data records are read during each iteration of the DATA step?
A. 1
     
B. 2
     
C. 3
     
D. 4

The answer is B.

Solution:
>> The first reading is
input @1 Company $20. @25 State $2. @;


>> The second reading is
input NumEmployees;
  

Explanations:
For the first reading, the single trailing @ option holds a raw data record in the input buffer until SAS
* executes an INPUT statement with no trailing @, or
* reaches the bottom of the DATA step.