The correct answer is D. Functions can be called, or invoked, only once in a program.
A function is a block of code that performs a specific task. Functions allow programmers to break large and complex problems into small and manageable tasks. Functions also allow programmers to use existing code to perform common tasks. Programmer-defined functions can be either value-returning or void.
A function can be called, or invoked, multiple times in a program. This is because a function is a reusable piece of code. When a function is called, the code inside the function is executed. The value returned by the function, if any, is then used in the calling code.
Here is an example of a function in Python:
def add_numbers(x, y):
return x + y
This function takes two numbers as input and returns their sum. The function can be called multiple times in a program, as shown in the following code:
x = 10
y = 20
z = add_numbers(x, y)
print(z)
This code will print the value 30, which is the sum of 10 and 20.