How do you join two datasets in a Cartesian product in SAS?

To create a Cartesian product between two datasets in SAS, using a CROSS JOIN in PROC SQL is the appropriate method. A Cartesian product occurs when every row in the first dataset is paired with every row in the second dataset, which is precisely what a CROSS JOIN does. In PROC SQL, this is achieved simply by listing both tables in the FROM clause without specifying any ON or USING clause for joining conditions. The result will be a new dataset that contains all possible combinations of the rows from both datasets.

In contrast, the other options do not produce a Cartesian product. Utilizing the MERGE statement in a DATA step requires a sorted dataset and relies on matching criteria, which would not create a Cartesian product but rather join rows based on common keys. Specifying matching criteria in a PROC SORT step is used to prepare datasets for merging, but again, this doesn't facilitate a Cartesian product either. Finally, listing both datasets in a DATA step with matching statements implies the establishment of criteria for joining them based on common variables, which again would not yield a Cartesian product.