Certified Associate in Python Programming (PCAP) Practice Exam 2025 - Free Python Programming Certification Questions and Study Guide

The method to convert a string to lowercase in Python is by using the `lower()` method, which is called on the string object itself. When you use `s.lower()`, it invokes the built-in `lower()` function associated with the string `s`. This function processes the string and returns a new string where all the uppercase letters have been converted to their corresponding lowercase letters.

In Python, calling `s.lower()` is a standard and efficient way to ensure that the contents of the string are represented in lowercase. This approach is integral to string manipulation within Python and conforming to object-oriented principles, as it operates directly on the string instance.

Other options do not represent valid methods for converting a string to lowercase in Python. For instance, `lowercase(s)` and `toLower(s)` do not exist as built-in functions or methods in Python. Similarly, `str.lower(s)` implies that `lower()` should be called as a function of the string class, which is incorrect; it should specifically be called on an instance of a string. Thus, the best practice and correct method for converting a string to lowercase in Python is indeed with `s.lower()`.