Task: Question Answering
Input (English): Mosquito fish found on the islands of the Bahamas live in various isolated freshwater ponds that were once a single body of water. When several male and female mosquito fish are taken from two isolated ponds and placed into a single pond, the breeding preference of each mosquito fish is for fish from its own original pond. Which of these most likely resulted in this breeding preference?  
 (A) Availability of food influenced the breeding preferences of the fish. (B) Competition for a suitable mate influenced the breeding preferences. (C) Predators in the pond influenced the breeding preferences of the fish. (D) Speciation due to reproductive isolation influenced the breeding preferences.
Output (English): D