Limited choice screen resolution

Unity Engine
1

How do I make the permission settings I need in this code, giving only those options that I indicated to choose from?

    public void SetResolution(int index)//the "On click" function on the resolutions buttons.
    {
        wantedResX = resolutions[index].width;
        wantedResY = resolutions[index].height;
        Screen.SetResolution(wantedResX, wantedResY, fullScreenMode);
        currentResolutionText.text = wantedResX + "x" + wantedResY;
    }
2

Remove those that are not to be chosen from the resolutions-array and from the player choice.
Why offer them to be chosen in the first place?