Which of these is not part of the function definition?

The correct understanding of function definitions emphasizes the critical components that make up a function in programming. A function definition typically includes its name, a list of parameters defined within parentheses, and a return type to specify what kind of value the function will send back after execution.

The claim regarding a set of square brackets with the code inside them is not accurate because functions are generally defined using curly braces or indentation (depending on the programming language) to encapsulate the block of code that the function executes. In many programming languages, square brackets are not used to define the scope or content of a function. Therefore, this is why the option about square brackets is not part of a proper function definition.

The other components - the function name, parameters, and return type - are indeed essential elements of a function definition. The function name uniquely identifies the function, the parameters act as placeholders for the arguments that will be passed when the function is called, and the return type indicates what type of value the function will return to the caller, if any. Understanding these components is essential for constructing and using functions effectively in programming.