What variables are written to the dataset Work.Ds3?

The dataset Work.Ds3 includes the variables Look1, Look2, and Look3 based on how these variables are derived or created in the data step prior to writing them out. When data is processed in a SAS data step, any variable that has been properly defined and initialized will be included in the output dataset unless explicitly excluded or if there are issues that prevent those variables from being generated.

In this scenario, if Look1, Look2, and Look3 have been assigned values and there are no errors in the preceding operations (like creating those variables correctly), they will all be written to the resulting dataset. This indicates that the program has executed properly and captured the data as intended.

Choosing this option implies a correct understanding of how SAS data steps operate and how variable creation and dataset output work, where all specified variables are included unless stated otherwise or if an error occurs. This understanding is crucial for effective SAS programming, as it allows for accurate data manipulation and management within SAS.