Given an trivia question precisely answer the question with a word/phrase/name. External resources such as Wikipedia could be used to obtain the facts.

Graca Machel, the widow of a President of Mozambique, is the wife of which famous man?
nelson mandela

The Up! and Eos and CC are models of which car brand?
volkswagen

Who is credited with the phrase I think, therefore I am?

rene descartes