Explanation:

The correct answer is option D, International Civil Aviation Organisation (ICAO), which does not have its headquarters in Geneva.

World Trade Organisation (WTO):
- The World Trade Organisation (WTO) is an international organization that deals with global rules of trade between nations.
- It was established on January 1, 1995, and its headquarters are located in Geneva, Switzerland.
- The WTO aims to promote free and fair trade by reducing barriers and regulating trade disputes among its member countries.
- It has 164 member countries as of 2021.

World Health Organisation (WHO):
- The World Health Organisation (WHO) is a specialized agency of the United Nations responsible for international public health.
- It was established on April 7, 1948, and its headquarters are located in Geneva, Switzerland.
- The WHO works to improve global health, prevent diseases, and promote health equity.
- It provides leadership and coordination in response to health emergencies and supports countries in strengthening their health systems.
- The WHO has 194 member countries as of 2021.

International Labour Organisation (ILO):
- The International Labour Organisation (ILO) is a United Nations agency that sets international labor standards and promotes decent work for all.
- It was established on April 11, 1919, and its headquarters are located in Geneva, Switzerland.
- The ILO promotes social justice and internationally recognized labor rights, including the elimination of forced labor, child labor, and discrimination in the workplace.
- It brings together governments, employers, and workers' organizations to develop policies and programs to improve working conditions and protect workers' rights.
- The ILO has 187 member countries as of 2021.

International Civil Aviation Organisation (ICAO):
- The International Civil Aviation Organisation (ICAO) is a specialized agency of the United Nations that sets international standards and regulations for aviation safety, security, efficiency, and environmental protection.
- It was established on December 7, 1944, and its headquarters are located in Montreal, Canada, not Geneva.
- The ICAO works to ensure the safe and orderly development of international civil aviation and fosters cooperation among its 193 member countries.
- It sets standards for aircraft operations, air navigation services, airports, and aircraft maintenance, among others.

Therefore, the correct answer is option D, International Civil Aviation Organisation (ICAO), as it does not have its headquarters in Geneva.