For the following code, which statement is NOT true?

public class Sphere

$\{$

private double radius;

public double $x$;

private double $y$;

private double $z$;

The $z$ field is available to code written outside the Sphere class.

The radius, $x,y,$ and $z$ fields are members of the Sphere class.

The $x$ field is available to code that is written outside the Sphere class.

The radius field is not available to code written outside the Sphere class.