The Ramsar Convention is an international treaty aimed at the conservation and sustainable use of wetlands, recognizing the ecological functions of these ecosystems and their economic, cultural, scientific, and recreational value.

Option 1: This option suggests making these sites completely inaccessible to humans, which is inconsistent with the convention as it advocates for sustainable use not absolute isolation.

Option 2: This option suggests permitting tourism and recreation only. While these are valid uses, the Ramsar Convention emphasizes a broader range of sustainable uses, not just tourism and recreation.

Option 3: This option suggests a period of no usage followed by sustainable usage. While this could help restore ecosystems, the Ramsar Convention doesn`t specify any non-use periods. It promotes continuous sustainable use.

Option 4: This option proposes to conserve all the sites through an ecosystem-based approach and allows their simultaneous sustainable use. This aligns with the Ramsar Convention`s principles, hence making it the correct answer. This approach ensures the conservation of biodiversity while also allowing human benefit through the sustainable use of these ecosystems.