World Hemophilia Day is observed globally to raise awareness about hemophilia and other bleeding disorders and to support affected patients and families. On which date is World Hemophilia Day commemorated each year?

Introduction / Context:
World Hemophilia Day is an important health observance focusing on hemophilia and other inherited bleeding disorders. It seeks to improve diagnosis, treatment, and quality of life for people living with these conditions. For general knowledge and medical awareness questions, knowing the correct date of this day helps demonstrate familiarity with key international health campaigns.

Given Data / Assumptions:

• The observance is called World Hemophilia Day.
• It is organised internationally and repeated annually.
• The question asks for the fixed date of observance.
• All options are dates in April, which requires careful discrimination.

Concept / Approach:
World Hemophilia Day is commemorated every year on 17 April. The date was chosen in honour of the birthday of Frank Schnabel, founder of the World Federation of Hemophilia. When answering, remember that this day falls between mid and late April and is often mentioned along with other April health observances in current affairs books.

Step-by-Step Solution:
Step 1: Recall that World Hemophilia Day is linked to a specific mid April date.Step 2: Identify from your memory that the exact date is 17 April.Step 3: Check the options and locate 17 April, which is option D.Step 4: Notice that the other options 15 April, 18 April, and 21 April are nearby but not correct.Step 5: Select option D as the final answer.

Verification / Alternative check:
To verify, you can recall that the World Federation of Hemophilia and health ministries around the world consistently mark 17 April with campaigns, awareness talks, and symbolic lighting of buildings in red. Many exam guides specifically highlight 17 April as World Hemophilia Day, often mentioned together with 18 April as World Heritage Day and 21 April as National Civil Services Day in India. This pattern of dates can be used as a cross check.

Why Other Options Are Wrong:
18 April corresponds to the International Day for Monuments and Sites or World Heritage Day and is not related to bleeding disorders.

15 April is not associated with World Hemophilia Day in standard international calendars and appears here as a trap option.

21 April is recognised for other observances such as National Civil Services Day in India and does not commemorate hemophilia.

Common Pitfalls:
Because many health and heritage related days fall in April, candidates may mix up the dates or assume that World Hemophilia Day falls on the same date as another well known observance. It is easy to confuse 17 April with 18 April or 21 April if you rely only on approximate memory. The best way to avoid this is to memorise a mini sequence, for example 17 April for hemophilia awareness, 18 April for monuments and sites, and 21 April for civil services, so that each date is clearly anchored in your mind.

Final Answer:
The correct date is 17 April.