March 21 is observed internationally as which special environmental day?

Introduction / Context:
Environmental observance days are a favourite topic in general knowledge and environment sections of competitive exams. March 21 is an important date in this context because it is observed as World Forestry Day, also widely known as International Day of Forests. The aim is to highlight the importance of forests for biodiversity, climate regulation, and human livelihoods. Correctly matching this date with the right environmental day is essential for scoring well on static GK questions.

Given Data / Assumptions:

• The question focuses on the specific date of 21 March.
• It asks which special environmental day is observed on this date.
• Options mention World Environment Day, World Forestry Day, a generic World Greenery Day, and a none of these choice.
• We assume the candidate is expected to recall the standard list of environment related days and their exact dates.

Concept / Approach:
World Forestry Day, now often celebrated as International Day of Forests, is observed on 21 March. Its purpose is to raise awareness about the role of forests in sustaining life on Earth and to encourage efforts for conservation and sustainable management. On the other hand, World Environment Day falls on 5 June, so it should not be linked to 21 March. Thus the correct conceptual link is 21 March equals World Forestry Day, which the candidate must recall accurately.

Step-by-Step Solution:
Step 1: Note the date in question, which is 21 March. Step 2: Recall from environment GK that 21 March is connected with forests and forestry. Step 3: Remember that the formal observance on this date is World Forestry Day or International Day of Forests. Step 4: Look at the options and locate World Forestry Day among them. Step 5: Select option B, World Forestry Day, as it correctly matches the environmental day observed on 21 March.

Verification / Alternative check:
Students can verify this information using environment and ecology textbooks, especially sections dealing with forest resources, where important days are often listed. Many competitive exam notes present a month wise table that shows 21 March as World Forestry Day and 22 March as World Water Day, forming a sequence that is easy to remember. United Nations and FAO sources also refer to 21 March as International Day of Forests, which confirms the correctness of this mapping.

Why Other Options Are Wrong:
Option A, World Environment Day, is observed on 5 June and focuses on general environmental awareness, so linking it with 21 March is incorrect.
Option C, World Greenery Day, is not a standard widely recognised environmental observance in major exam syllabi.
Option D, None of these, is wrong because a correct and well known observance, World Forestry Day, does exist for 21 March.

Common Pitfalls:
Candidates sometimes confuse World Forestry Day with World Environment Day because both are related to nature and conservation. Another common error is to remember that 21 March is important but mislabel it with a generic term such as greenery day instead of the correct formal title. To avoid this, it is useful to memorise the short sequence: 21 March World Forestry Day, 22 March World Water Day, and then later 5 June World Environment Day. This pattern helps keep the dates distinct in memory.

Final Answer:
March 21 is observed internationally as World Forestry Day.