How do you create a function in Python?

In Python, a function is defined using the 'def' keyword, which is followed by the function name and parentheses. The syntax looks like this:

def function_name(parameters):

function body

This structure clearly indicates to the Python interpreter that you are defining a new function. The 'def' keyword specifically signals the beginning of a function definition, making it integral to the process of creating functions in Python.

After this, you can include parameters within the parentheses if necessary, which allows you to pass values into your function. Following this, the function body is indented and contains the code that will execute when the function is called.

The other options presented do not follow the correct Python syntax for defining a function, which is why they do not work. Therefore, the use of 'def' is the established and correct way to create a function in Python, making this choice the right one.