Answer choice B is correct because it does not use any opinions
The sound of a ringing telephone is more likely to bring about a reaction from me.
A ringing telephone has some sort of urgency to it: someone wants or needs to speak to me. It might be good or bad news, it might just be an old friend or relative who wants to chat... It's a sound that makes me curious. I want to know who it is and what that person has to say.
The smell escaping from a bakery is less urgent. If I'm hungry, it'll be more appealing. If not, even though it smells delicious, I will not be as inclined to pay the bakery a visit. It might even awaken some memories, still it's not likely to make me interrupt my walk to wherever it is that I'm going.
The answer is C. This is because two professors (who do this stuff for a living) are likely the most credible source rather than people who don't list sources, student reports, or personal blogs.
Cellphones should be used in class
