What changes should be made to the KEEP statement to correct the errors in the LOG?

After a SAS program is submitted, the following is written to the SAS log:

105 data january;

106 set allmonths(keep = product month num_sold cost);

107 if month = ‘Jan’ then output january;

108 sales = cost * num_sold;

109 keep = product sales;

——

22

ERROR 22-322: Syntax error, expecting one of the following:!, !!, &, *,**, +, -,/, <,< =, <>, =, >, ><, >=,

AND, EQ, GE, GT, IN, LE, LT, MAX, MIN, NE, NG, NL, NOTIN, OR,^=,|,II,

110 run;

What changes should be made to the KEEP statement to correct the errors in the LOG?
A . keep product sales;
B. keep product, sales;
C. keep = product, sales;
D. keep = (product sales);