The correct answer is: A. National parks
A national park is a protected area of land that is set aside for conservation and recreation. National parks are often home to unique ecosystems and wildlife, and they play an important role in protecting these resources.
Forests are also important for conservation, but they are not considered to be on-site conservation methods. Forests are managed by humans, and they are often used for timber production or other commercial purposes. This can lead to deforestation, which is the destruction of forests.
Zoos are not considered to be on-site conservation methods either. Zoos are facilities where animals are kept in captivity for educational or entertainment purposes. While zoos can play a role in conservation by breeding endangered species, they do not provide the same level of protection as national parks.
Parks are also not considered to be on-site conservation methods. Parks are areas of land that are set aside for public use, such as recreation or picnicking. While parks can be important for conservation, they do not provide the same level of protection as national parks.
In conclusion, the correct answer is: A. National parks. National parks are protected areas of land that are set aside for conservation and recreation. They play an important role in protecting unique ecosystems and wildlife.