Correct Answer: To stay up late working or studying

Solution : The correct choice is the second option.

The idiom "to burn the midnight oil" originates from the idea of working late into the night when traditionally people used oil lamps for illumination. It figuratively means putting in extra effort or working diligently during night-time hours.

So, if someone says they are burning the midnight oil, it implies that they are working late or putting in extra hours to accomplish a task or meet a deadline.