Comprehensive and Detailed Explanation From Exact Extract:

A valid function call invokes a function by its name, providing the required number and type of arguments in the correct syntax. According to foundational programming principles (e.g., Certiport Scripting and Programming Foundations Study Guide), function calls must follow the language's syntax rules, typically function_name(arguments).

Option A: 'function sample(float 2.0).' This is incorrect. This resembles a function definition (declaring a function named sample with a parameter), not a function call. A call would be sample(2.0).

Option B: 'GetHeight(integer 3, 4).' This is incorrect. The syntax integer 3 is invalid in most languages for a function call. A correct call might be GetHeight(3, 4), assuming GetHeight accepts two integers. The inclusion of type keywords (integer) is not typical in function calls.

Option C: 'round(4.723, 2).' This is correct. In languages like Python, round(4.723, 2) is a valid call to the built-in round function, which takes a float and an integer (number of decimal places) and returns a rounded value (e.g., 4.72).

Option D: 'PrintSample().' This is correct. Assuming PrintSample is a defined function with no parameters, PrintSample() is a valid call (e.g., in Python: def PrintSample(): print('Sample')).

Certiport Scripting and Programming Foundations Study Guide (Section on Functions and Function Calls).

Python Documentation: ''Built-in Functions'' (https://docs.python.org/3/library/functions.html#round).

W3Schools: ''C Functions'' (https://www.w3schools.com/c/c_functions.php).