default parameter specifiers are not permitted

Ive been trying to build the following code that comes up with 3 of the same errors “default parameter specifiers are not permitted”.

public static void SetCameraBounds(Camera cam = null) {                   // error
	// If no Camera was passed in, use the main Camera
	if (cam == null) cam = Camera.main;
	// This makes a couple of important assumptions about the camera!:
	//   1. The camera is Orthographic
	//   2. The camera is at a rotation of R:[0,0,0]
	// Make Vector3s at the topLeft and bottomRight of the Screen coords
	Vector3 topLeft = new Vector3( 0, 0, 0 );
	Vector3 bottomRight = new Vector3( Screen.width, Screen.height, 0 );
	// Convert these to world coordinates
	Vector3 boundTLN = cam.ScreenToWorldPoint( topLeft );
	Vector3 boundBRF = cam.ScreenToWorldPoint( bottomRight );
	// Adjust their zs to be at the near and far Camera clipping planes
	boundTLN.z += cam.nearClipPlane;
	boundBRF.z += cam.farClipPlane;
	// Find the center of the Bounds
	Vector3 center = (boundTLN + boundBRF)/2f;
	_camBounds = new Bounds( center, );
	// Expand _camBounds to encapsulate the extents.
	_camBounds.Encapsulate( boundTLN );
	_camBounds.Encapsulate( boundBRF );

// Checks to see whether the Bounds bnd are within the camBounds //error
public static Vector3 ScreenBoundsCheck(Bounds bnd, BoundsTest test = {
	return( BoundsInBoundsCheck( camBounds, bnd, test ) );

// Checks to see whether Bounds lilB are within Bounds bigB //error
public static Vector3 BoundsInBoundsCheck( Bounds bigB, Bounds lilB, BoundsTest test = BoundsTest.onScreen ) {

I’ve already looked at the solution to the problem at Default Parameter Specifiers Are Not Permitted - Unity Answers. The solution says to go change something in the project options, but my project options is grayed out. What do i need to do to fix this?

You have to select your project in the Solution Pad in order to have the “Assembly-CSharp Options” button enabled. A solution can contain multiple projects. The easiest way is to select the project “Assembly-CSharp” in the solution pad and right click on it. There you will also find a button called “Options” (almost at the bottom).