Thanks to the efforts of environmentalists, people are becoming better aware of the problems of endangered species.

• A. 
  Environmentalists are expressing their gratitude towards people who are better aware of the problems of endangered species.
• B. 
  People owe their growing awareness of the problems of endangered species to the efforts of the environmentalists.
• C. 
  People have no idea about the problems of endangered species in spite of the efforts of environmentalists.
• D. 
  Environmentalists are doing their best to make people aware of the problems of endangered species.