In which of following system, scientific data can be exchanged between different parts of the world?

[A] : Flora and Fauna of different parts of the world do not show uniform pattern of distribution . [R] : This may be attributed to the presence of barriers between different parts of the world .

[A] : Flora and Fauna of different parts of the world do not show uniform pattern of distribution . [R] : This may be attributed to the presence of barriers between different parts of the world .

[A] : Flora and Fauna of different parts of the world do not show uniform pattern of distribution . [R] : This may be attributed to the presence of barriers between different parts of the world .

[A] : Flora and Fauna of different parts of the world do not show uniform pattern of distribution . [R] : This may be attributed to the presence of barriers between different parts of the world .

Which of the following is not a problem of barter system of exchange