Fred ______ driving on the highway until morning.

• A. Kept on
• B. Continued
• C. Went on
• D. Carried on

Answer: (A)

This item tests choosing a phrase that expresses continuing an action over time. “Keep on” is a natural phrasal verb meaning to continue doing something, and when paired with the -ing form, it emphasizes that the action kept going through the night: Fred kept on driving on the highway until morning. The other options are understood, but they sound less natural in this exact sentence: “continued” is more formal, while “went on” and “carried on” are acceptable but less smooth in everyday speech. So the best choice for a natural, idiomatic feel is the one that uses the phrasal verb meaning to persist.