Which of the following statements about closures is true?

The statement that closures can be used to create private variables for functions is true because closures allow functions to maintain access to their lexical scope even when the function is executed outside that scope. When a function is defined within another function, it can reach variables in the outer function's scope. This characteristic is what enables developers to create private variables—by keeping these variables encapsulated within the outer function, they are not accessible from the global scope or outside the creating function, thus implementing a form of data hiding.

For example, in JavaScript, you can define a function that returns another function, and the inner function can access the variables defined in the outer function. This is particularly useful in module patterns and when you want to protect certain data from being manipulated directly.

This capability of closures to maintain a reference to outer function variables ensures that the internal state can be securely managed and manipulated through specific functions, resulting in behavior that isn't easily tampered with from the outside.