The students' week was rounded … with a dance.

Analyze the question: This is a phrasal verb question. We need the particle that combines with "rounded" to mean "ended or completed."

Explain the concept: "Round off" means to finish or complete something in a satisfying or fitting way, often with a final activity. For example:

• "He rounded off the meal with coffee."
• "The party was rounded off with a dance."

Check each option:

• A. off: "rounded off" means concluded or ended, which fits perfectly.
• B. up: "round up" means to gather together (e.g., round up the cattle) or to raise a number to the nearest whole number. It does not fit here.
• C. out: "round out" means to make something complete or fuller. It is used less often and is not the standard idiom for ending an event.
• D. down: "round down" means to lower a number to the nearest whole. It does not fit.

Solution: The sentence reads: "The students' week was rounded off with a dance." The dance was the closing event of the week, so "rounded off" is the correct phrasal verb.

Tip: Remember "round off" = "end nicely." If a sentence describes something ending with a final event (a dance, a party, a speech), think round off. Remember "round up" for gathering things or numbers.