Explanation:

- The committee wanted us to explain this in detail. "Explain" means to make something clear or understandable, often by providing more information or details.

- Option 1: Elaborate

- Elaborate means to explain something in detail or to add more information.

- This is the best synonym for "explain" in the context of providing detailed information.

- Option 2: Trouble

- Trouble means to cause problems or distress.

- It does not fit the meaning of explain.

- Option 3: Collect

- Collect means to gather together multiple items or pieces of information.

- It doesn't mean to explain or clarify.

- Option 4: Keen

- Keen means having or showing eagerness or enthusiasm.

- It is not a synonym for explain.