Answer (a) — incorrect: Although the second outbreak occurred in the Star Hospital, the affected personnel live all around the city (aside from the five medical residents who live in the housing near the hospital). If you created a spot map by place of work, you would have observed clustering around the hospital.

Answer (b) — correct: You observe clustering around the Amoy Apartment Complex because most of the cases have the same place of residence. Your map confirms a geographic clustering of cases around the apartment complex. You add place of residence as a necessary component of your case definition.

Answer (c) — incorrect: You do observe a clustering of cases around the Amoy Apartment Complex.