Explanation:

- Option 1 (2000): This year was significant for the millennium celebration, but not for the International Year of Freshwater.

- Option 2 (2009): Known as the International Year of Astronomy, highlighting the advancements in that field.

- Option 3 (2007): This year was designated as the International Year of the Dolphin, focusing on marine conservation.

- Option 4 (2003): This was declared the International Year of Freshwater by the United Nations to emphasize the importance of sustainable freshwater management.