The correct answer is: at.
The preposition “at” is used to indicate a specific point in time or space. In this case, the speaker is indicating that they take a quick look at the newspaper headlines. This means that they are not reading the entire newspaper, but are simply glancing at the headlines to get a general idea of what is happening in the world.
The other prepositions in the list are not as appropriate in this context. “Of” is used to indicate a part of something, “over” is used to indicate movement across something, and “on” is used to indicate a position on something. None of these prepositions accurately describes the speaker’s actions.
Therefore, the correct answer is “at.”