On the topic "remote work and urban real estate," the coordinator sends the same broad brief to three web search subagents. Their combined results contain the same dozen widely cited articles three times over, while commercial office vacancy data, residential migration, and municipal tax effects are barely covered. What change best improves coverage?

Answer: D — Partition the research scope across the subagents, assigning each a distinct subtopic or source type, such as office vacancy data, residential migration, and municipal finance.

Giving every subagent the same brief produces duplication; partitioning scope by distinct subtopics or source types minimizes overlap and spreads coverage (task 1.2). Deduplication in synthesis (a) tidies citations but can't add coverage that was never gathered. More subagents with the same brief (b) multiply the duplication. More results per query (c) adds cost and noise without directing any effort at the gaps.