In the given code, the class Foo has a private method a() returning 'Hello world!'. The class Bar extends Foo and overrides the method a() with protected visibility, returning 'Bonjour le monde!'. The class Baz extends Bar but does not override the method a(). When calling the b() method on instances of Foo, Bar, and Baz, the following will happen: - `new Foo().b()` will call Foo's b(), which calls Foo's private a(). So, it returns 'Hello world!'. - `new Bar().b()` will call Foo's b() (since b() is not overridden in Bar), which calls Bar's overridden a(), so it returns 'Bonjour le monde!'. - `new Baz().b()` will call Baz's b(), which calls Bar's overridden a(), so it returns 'Bonjour le monde!'. Thus, the output will be 'Hello world!', 'Bonjour le monde!', and 'Bonjour le monde!', matching option C.