March 15 is observed as –

The correct answer is: B. United Nations Day for South-South Cooperation

South-South cooperation is a term used to describe the development cooperation that takes place between developing countries. It is based on the idea that developing countries can learn from each other’s experiences and share resources in order to achieve sustainable development.

The United Nations Day for South-South Cooperation is observed on March 15 each year. It was established by the United Nations General Assembly in 2005 to promote South-South cooperation and to highlight the importance of this type of development cooperation.

The other options are incorrect because:

• World Cancer Day is observed on February 4 each year.
• World Telecommunication Day is observed on May 17 each year.
• International Human Solidarity Day is observed on December 20 each year.