Sorry, Pondedaniel, but "Could it be this one?" sounds very Portuglish to me. Maybe I would use it if threatened with a gun, I were offered a large sum of money to do so, or kidnappers were holding my son for ransom. It simply doesn't sound natural to my ears. Maybe my ears are just werid. No offense. When offered food or drink that I did not want, I used to answer "Nao, obrigado, estou bem," A girlfriend told me several times that she had no idea what I was saying or what I meant. I was using Portuguese words but the answer (thought) was in English. "I am fine" or "I am okay" is a perfectly good response in English. It isn't enough to translate a thought or comment, it should be consistent with the culture of the language. My response was not. If you want to ask "Could it be this one?", you will be understood. I am not attempting to force you to do one thing or another. I am just expressing an opinion. OK?
Márcio, I agree with your observation, but weak or evasive answers exist. I'm sure you've also heard, "I'mnot saying that I will and I am not saying that I won't." How's that for wishy-washy?