I would also agree with both your answers. What I would do is try the cin thing, and take the specific error to your teacher.
For the other one - you can't PROVE it, but any answer other than D is ridiculous. The compiler ignores whitespace, so A can't be it. The only reason D wouldn't be the correct answer is if you're trying to obfuscate it, and that's me TRYING to be ridiculous.
