pollution/ coast of Florida/ kill/ coral reefs/ serve/ habitat/ hundreds of species of fish/

• A. 
  Pollution off the coast of Florida' has killed the coral reefs served as habitat for hundreds of species of fish.
• B. 
  Pollution off the coast of Florida has killed the coral reefs serving as habitat for hundreds of species of fish.
• C. 
  Pollution off the coast of Florida is killing the coral reefs, which serve as habitat for hundreds of species of fish.
• D. 
  Pollution off the coast of Florida killed the coral reefs serves as habitat for hundreds of species of fish.