What does the expression '5 in my_list' evaluate to?

The expression '5 in my_list' evaluates to a boolean value indicating whether the integer 5 is one of the elements present in the list named my_list. This is accomplished through the use of the in keyword, which is specifically designed to check for membership within collections such as lists, tuples, sets, and dictionaries. If 5 exists in my_list, the expression returns True; if not, it returns False.

This fundamental operation is crucial for conditions and loop iterations, making it easier to work with data structures in Python. The other options represent different operations that are not associated with the in keyword's functionality. For instance, you do not check for the largest number, count occurrences, or retrieve an index with the expression '5 in my_list'; these would require different methods or expressions altogether.