The correct answer is C. either value-returning or void functions.
A programmer-defined function is a function that is created by the programmer. It can be either a value-returning function or a void function. A value-returning function returns a value to the calling function, while a void function does not return a value.
Here is an example of a value-returning function:
python
def add_numbers(x, y):
return x + y
This function takes two numbers as input and returns their sum.
Here is an example of a void function:
python
def print_message():
print("Hello, world!")
This function does not take any input and does not return a value. It simply prints the message “Hello, world!” to the console.
In conclusion, programmer-defined functions can be either value-returning or void functions.