Which functions can be used within a conditional expression?

Which functions can be used within a conditional expression?
A . FUNCTION funca()
DEFINE ret_code integer
LET ret_code = 10
END FUNCTION
B . FUNCTION funca()
DEFINE ret_code integer
LET ret_code = 10
RETURN ret_code
END FUNCTION
C . FUNCTION funca()
DEFINE ret_code integer
LET ret_code =10 LET ret_code2 = 20
RETURN ret_code, ret_code2
END FUNCTION
D . FUNCTION funca(param)
DEFINE ret_code, param integer
LET ret_code = param * 10
RETURN ret_code
END FUNCTION

View Answer

Answer: BD