In the context of optimizing the start$\_$date$\_$report.py script, what is the primary role of the get$\_$same$\_$or$\_$newer$()$ function?

The function calculates the total number of employees starting on a specific date.

The function filters and processes employee data based on start dates.

The function is used to sort data by employee start dates.

The function is responsible for generating graphical representations of the data.