World Hydrography Day (WHD) is observed annually on which date to highlight the importance of hydrography and safe navigation?

Introduction / Context:
World Hydrography Day is an international observance that aims to raise awareness about hydrography, which involves the measurement and description of the physical features of oceans, seas, coastal areas, lakes, and rivers. Hydrographic information is critical for safe navigation, marine environmental protection, and coastal zone management. This question asks for the exact date on which World Hydrography Day is celebrated each year.

Given Data / Assumptions:

• The observance is World Hydrography Day, often abbreviated as WHD.
• It is held every year on a fixed date in June.
• The options provide several closely spaced dates in June.
• Only one of these dates corresponds to the officially recognised date for WHD.

Concept / Approach:
The International Hydrographic Organization selected a specific date to celebrate World Hydrography Day and to recognise the role of hydrographers worldwide. The chosen date is 21 June, which also marks the anniversary of the establishment of earlier hydrographic institutions. For exam purposes, students must simply memorise that 21 June is linked with hydrography and marine charting, not with other June observances.

Step-by-Step Solution:
Step 1: Recall that World Hydrography Day is a June observance related to the mapping of seas and waterways.Step 2: From general knowledge references, remember that 21 June has been designated as World Hydrography Day.Step 3: Look at the options and identify 21 June as option C.Step 4: Confirm mentally that other important June days like World Environment Day fall on different dates, such as 5 June.Step 5: Select 21 June as the correct answer.

Verification / Alternative check:
Information from international maritime and hydrographic organisations consistently shows that World Hydrography Day is observed on 21 June. On this date, many countries organise conferences, workshops, and exhibitions dealing with nautical charts, bathymetric surveys, and safe navigation. No such consistent pattern exists for 20 June, 22 June, 23 June, or 25 June, which confirms that 21 June is the correct observance date.

Why Other Options Are Wrong:
23 June: This date is close in the calendar but is not officially tied to World Hydrography Day.

22 June: Another adjacent date included as a distractor; it does not match the international observance.

20 June: Slightly earlier than the correct date and not associated with WHD in standard references.

25 June: This may be important for other maritime events in some contexts, but it is not the date selected for World Hydrography Day.

Common Pitfalls:
Because the options list only dates that are very close to each other, students who remember only that the day falls in late June may guess incorrectly. To avoid this, one can tie 21 June firmly with the idea of charting oceans and waterways. Linking dates to themes in this way, such as 21 June for hydrography and 5 June for environment, builds a stronger mental map of important international observances.

Final Answer:
21 June