Final answer:
Class objects can be passed both by reference and by value to a function. The statement that they can be passed by reference only is false.
Step-by-step explanation:
Class objects can be passed both by reference and by value to a function in programming languages like C++. However, passing by reference is often preferred because it avoids copying the object, which can be more efficient, especially for large objects. This is done by using reference (&) or pointer (*) operators in the function declaration. Therefore, the statement that class objects can be passed by reference only, is false. Similarly, looking at the examples provided, all reflect the concept of true or false questions related to various subjects, emphasizing the importance of understanding concepts thoroughly to determine their validity.