On which date is the International Day of Happiness celebrated each year across the world as proclaimed by the United Nations to recognise the importance of happiness in people lives?

Introduction / Context:
The International Day of Happiness is an official United Nations observance that highlights the importance of happiness and well being as universal goals. It is marked by activities and campaigns encouraging positive mental health and social progress. The question checks whether candidates know the exact date on which this day is celebrated.

Given Data / Assumptions:

• The day is recognised by the United Nations.
• The focus is on happiness as a global priority.
• Four possible dates in March are provided as options.
• The correct date must be identified from among these close alternatives.

Concept / Approach:
This is a factual recall question related to important international days. The United Nations proclaimed that the International Day of Happiness would be observed on 20 March each year. Remembering this date is useful not only for general awareness but also because many exam questions ask about specific UN observances.

Step-by-Step Solution:
Step 1: Recall that the International Day of Happiness falls in the month of March.Step 2: Try to remember the precise day within March that the United Nations selected.Step 3: Confirm from memory that the day is fixed as 20 March every year.Step 4: Choose option C, 20th March, as the correct answer.

Verification / Alternative check:
An alternative memory aid is that 21 March is often linked with the International Day for the Elimination of Racial Discrimination, so the happiness day comes one day earlier on the twentieth. This comparison helps keep the dates clear.

Why Other Options Are Wrong:
Option A: 21st March is associated with other UN observances, not the International Day of Happiness.
Option B: 23rd March is not the recognised date for this day.
Option D: 19th March is also incorrect and is a plain distractor without strong association.

Common Pitfalls:
Candidates may mix up dates of different UN days that occur close together in the calendar. Another common mistake is to guess 21 March simply because it appears in many other international observances, but that is not correct for this particular one.

Final Answer:
The International Day of Happiness is celebrated each year on 20th March.