Which of the following statements correctly initializes a list in Python?

The statement that correctly initializes a list in Python is the one that uses square brackets, as lists in Python are defined with this notation.

In Python, a list is an ordered collection of items that allows for duplicates and can hold a variety of data types. The correct initialization method, which uses square brackets, creates a list containing the elements 1, 2, and 3. This is how you can easily create a list to store multiple items together.

The other options use different syntax that does not correspond to the creation of a list. For example, parentheses denote a tuple, which is an immutable sequence type, while curly braces denote a set, which is an unordered collection of unique items. The last option incorrectly attempts to use semicolons to separate the list items, which is not valid syntax in Python for lists. Thus, the square bracket notation is essential for correctly initializing a list in Python.