How do parasites and hosts tend to co:evolve?

How do parasites and hosts tend to co:evolve?
  1. If the host evolves special mechanisms, the parasite must evolve to counteract them
  2. If the parasite evolves special mechanisms, the host must evolve to counteract them
  3. The host and parasite evolve independently of each other
  4. The host and parasite evolve together in a symbiotic relationship

Solution

Darwin notes that if the host evolves special mechanisms for rejecting or resisting the parasite, the parasite must evolve mechanisms to counteract and neutralise them.

Asked in: NCERT

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