. Mark the letter A, B, C, or D to indicate the sentence that is closest in meaning to each of the following questions

Eco-travellers have to prevent or minimize any negative impacts on the environment.

• 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.