The disease is mainly caused by a lack of a slippery substance in the lungs called surfactant. This substance helps the lungs fill with air and keeps the air sacs from deflating. Surfactant is present when the lungs are fully developed.
https://medlineplus.gov/ency/article/001563.htm
C. It's necessary for the survival of the individual
They must be separated to the point that their genetic makeup changes so that they can no longer breed.