Covariant return types

You are given the following hierarchy of classes:

class File { }

class TextFile extends File { }

class MediaFile extends File { }

class Soundtrack extends MediaFile { }

class Movie extends MediaFile { }

class Folder { }

There are two class loaders (but they don't work):

class BaseLoader {
    
    public MediaFile load(String path) {
        return new MediaFile(); // load and return
    }
}

class Loader extends BaseLoader {
    
    @Override
    public XXX load(String path) {
        return null; // just for example :)
    }
}

What class can be written instead of XXX to compile the code? Select all that apply.