A frequency report of the variable Jobcode in the Work.Actors data set is listed below.




The following SAS program is submitted:
data work.joblevels;
set work.actors;
if jobcode in ('Actor I', 'Actor II') then
joblevel='Beginner';
if jobcode='Actor III' then
joblevel='Advanced';
else joblevel='Unknown';
run;

QUESTION:Which of the following represents the possible values for the variable joblevel in the Work.Joblevels data set?
a. Advanced and Unknown only
b. Beginner and Advanced only
c. Beginner, Advanced, and Unknown
d. ' ' (missing character value)

选什么？为什么？