When all the items on the agenda had been discussed, the meeting was …

Analyze the question: The sentence says that all the items on the agenda had been discussed, so the meeting's business was finished. We need the word that describes formally ending a meeting.

Explain the concept: These words look similar, but each has its own use:

• Dismissed: used for sending people away, such as a class, a court case, or an employee. People are dismissed. A meeting is not normally dismissed.
• Postponed: means delayed until a later time. This doesn't fit, because the business was finished and nothing was being delayed.
• Adjourned: means formally brought to a close or suspended, whether until a later time or indefinitely. It is the standard word for ending a meeting, session, or court sitting.
• Dissolved: used for ending a parliament, a council, a partnership, or an organisation. It is also used for solids mixing into liquids. A single meeting is not dissolved.

Solution:

1. The agenda is finished, so the meeting must end formally.
2. "Postponed" is out, since nothing remains to be done later.
3. "Dissolved" and "dismissed" don't collocate with "meeting" in this sense.
4. "Adjourned" is the word used for formally closing a meeting: "The meeting was adjourned."

Answer: The correct option is C. adjourned.

Tip: Remember the chairman's phrase, "I now declare this meeting adjourned." Link adjourn with meetings and courts, dissolve with parliaments and organisations, and dismiss with people.