A parasite invades the species and causes its population to decline because a biotic factor is a living factor that affects a species
The homology of animals is based on scientists current understanding on the evolutionary history of living species.
Answer:
Oral poliovirus vaccine or Sabin vaccine, named for its inventor American physician and microbiologist Albert Sabin, was developed. OPV contains live attenuated (weakened) virus and is given orally.