Where is the headquarters of the Pan American Health Organization (PAHO), the regional health agency for the Americas, located?

Introduction / Context:
The Pan American Health Organization (PAHO) serves as the specialized health agency for the Americas and also functions as the regional office for the World Health Organization in this part of the world. Knowing the location of PAHO's headquarters is a typical static general knowledge question related to world and regional organizations responsible for public health.

Given Data / Assumptions:
• The organization in question is the Pan American Health Organization, dealing with health in North, Central and South America and the Caribbean.
• The options include four major cities in North America: Mexico City, Washington DC, Ottawa and New York.
• It is assumed that you can associate PAHO with the capital city of the United States, where many international and regional organizations maintain their headquarters.

Concept / Approach:
PAHO has a long history of coordinating health responses in the Americas and is closely linked with Washington DC. While New York is famous for global UN headquarters and Mexico City and Ottawa are important national capitals, PAHO's central administrative base is in Washington DC. Thus, the strategy is to recall this specific pairing and choose “Washington DC” from the options.

Step-by-Step Solution:
Step 1: Recall that PAHO was founded in the early twentieth century and later became the regional office for WHO in the Americas.Step 2: Remember that PAHO's main headquarters building, where its Director and executive bodies meet, is located in Washington DC.Step 3: Review the options and recognize that Washington DC is a well-known hub for international organizations operating in the Western Hemisphere.Step 4: Note that Mexico City, Ottawa and New York are important cities, but none of them is officially cited as the headquarters city of PAHO in standard exam references.Step 5: Conclude that Washington DC is the correct answer.

Verification / Alternative Check:
To verify this, think of news items or official press releases related to health emergencies in the Americas. Many such announcements come from PAHO offices in Washington DC. Additionally, PAHO is often described as being “headquartered in Washington DC” in introductory notes on world health bodies, confirming the correct choice.

Why Other Options Are Wrong:
• Mexico City: It is a major Latin American capital but is not the headquarters location for PAHO.
• Ottawa: Capital of Canada, important in international affairs, but not the city where PAHO is based.
• New York: This city hosts the main UN headquarters and several other agencies but not PAHO's central office.

Common Pitfalls:
Students sometimes automatically select New York whenever a UN-related agency is mentioned. Others may guess Mexico City because it is centrally located within Latin America. To avoid such mistakes, remember the specific association: PAHO equals Washington DC, just as WHO equals Geneva and the UN main secretariat equals New York.

Final Answer:
The headquarters of the Pan American Health Organization is located in Washington DC.