Final answer:
The statement is true for even functions, which are functions that satisfy the property f(-x) = f(x) for all x in the domain.
Step-by-step explanation:
The statement is true for even functions. An even function is a function that satisfies the property f(-x) = f(x) for all x in the domain. When an even function is composed with itself, the output values will be the same as the original function. For example, if f(x) = x^2 is an even function, then f(f(x)) = f(x^2) = (x^2)^2 = x^4. The output values of f(x) are the same as the output values of f(f(x)).