Step 1: Understanding the Concept:
Each global body has a defined area of work. Mental health falls under public health, which is the specific mandate of one of these four organisations.
Step 2: Why option A is correct.
The World Health Organisation (WHO) is the United Nations agency responsible for international public health, and it runs the world's main mental health programs and guidelines, such as its Mental Health Action Plan.
Step 3: Why the other options are wrong.
UNO (the United Nations Organisation) is the parent body over many specialised agencies, but health programs are run through WHO specifically, not the UN as a whole. NASA deals with space research, unrelated to health. UNESCO's mandate is education, science, and culture, not clinical or public health programs.
Final Answer:
WHO leads global mental health programs. This corresponds to option (A).