Which two correctly create a SAS date value?

To create SAS date values, the correct syntax involves specifying the date in a string format followed by the letter 'd'. This indicates to SAS that the string should be interpreted as a date value. Therefore, the correct answers are:

A. "10/19/2019"d - This format directly specifies the month, day, and year, enclosed in quotes followed by 'd', which SAS correctly interprets as a date value.

C. "19Oct2019"d - This format uses a three-letter abbreviation for the month combined with the day and year, also followed by 'd'. This is another valid way to specify a date in SAS.

Option B, mdy(10, 19, 2019), is incorrect because while the MDY function does create date values from month, day, and year components, the function itself should be used within a DATA step or another context where SAS functions are evaluated, and it doesn't directly create a date literal in the same way as options A and C.

Option D, mdy(19, Oct, 2019), is syntactically incorrect because the MDY function expects numeric arguments for the month, day, and year, and "Oct" as a literal month name is not a valid numeric argument.

References: SAS 9.4 Language Reference: Concepts.