What caused the error in the submitted SAS log for the DO statement?

The correct answer highlights the requirement for separating values within a DO statement in SAS programming. In a DO statement, values must be distinct and properly formatted for SAS to interpret them as separate items. Specifically, the values in a list should indeed be separated by commas, which allows the SAS system to recognize and process each value appropriately.

When values are not separated by commas, SAS may misinterpret the list and throw an error while attempting to execute the loop. This rule is essential for ensuring that SAS can correctly compile and run the DO statement without any ambiguity regarding the items included.

Understanding the formatting requirements for lists in a DO statement is crucial for effective SAS programming. This knowledge allows programmers to avoid common syntax issues that can result in execution errors.