The best option for the meaning of the expression is: a private conversation.
The French expression "tête-à-tête" means precisely that: a private conversation that usually takes place between two people. It could also involve more people as long as it's still intimate. This expression literally means "head-to-head", since the word <em>tête</em> comes from Old Frech <em>teste</em> (head.).
The answer is C because she or he is giving reasons like its not reasonable to prepare at the last minute on an exam then you would fail. It also says that if you don't prepare for a marathon you''ll probably get last place like a low grade on a exam.
