A. Any form of nature travel is sometimes mistaken as ecotourism.

B. Ecotourism can be sometimes mistaken for any form of nature travel.

C. Ecotourism can be sometimes mistaken as any form of nature travel.

D. Ecotourism is, to some people, mistaken as any form of nature travel.

A. Unless those areas are not damaged or destroyed, they will be available to future generations.

B. Because those areas are damaged or destroyed, they will not be available to future generations.

C. To keep them available to future generations, those areas must not be damaged or destroyed.

D. If damaged or destroyed, those areas will not be available to future generations any longer.

A. Tourists provide us with the principles of ecotourism throughout their trip.

B. We aim at providing the principles of ecotourism for tourists throughout their trip.

C. We provide ourselves with the principles of ecotourism through our trip.

D. We need more information about the principles of ecotourism for our trip.

A. Tourists are free to learn about the vital eco-systems before arriving.

B. It is optional for tourists to learn about the vital eco-systems before arriving.

C. Tourists are not required to learn about the vital eco-systems before arriving.

D. Tourists are required to learn about the vital eco-systems before arriving.

A. Eco-travellers are not required to protect the environment.

B. Eco-travellers are encouraged not to have any negative impacts on the environment.

C. It is eco-travellers' responsibility to prevent or minimize any negative impacts on the environment.

D. Eco-travellers have never had any negative impacts on the environment.