World Humanitarian Day is celebrated on 19th August. This day was designated by the United Nations General Assembly in 2008 to honor and recognize the efforts of humanitarian workers and to raise awareness about the importance of humanitarian work worldwide.

Option 1, 26th June, is not the correct answer. While there are other international days observed on this date, such as the United Nations International Day against Drug Abuse and Illicit Trafficking, it is not the date for World Humanitarian Day.

Option 2, 17th July, is also not the correct answer. There is no significant international day celebrated on this date that relates to humanitarian work.

Option 3, 19th August, is the correct answer. This is the official date designated by the United Nations for World Humanitarian Day.

Option 4, 27th September, is not the correct answer. While there are international days observed on this date, such as the United Nations World Tourism Day, it is not the date for World Humanitarian Day.

Overall, the correct answer is option 3, 19th August.