Many parasites have evolved to be $A$ in such a way that both host and the parasite tend to $B$; that is,if the host evolves special mechanisms for rejecting or resisting the parasite,the parasite has to evolve mechanisms to $C$ and neutralize them,in order to be successful with the same host species.
Choose the correct option for $A$,$B$,and $C$.

• A
  $A-$host-specific,$B-$evolve,$C-$counteract
• B
  $A-$host-specific,$B-$coevolve,$C-$counteract
• C
  $A-$source specific,$B-$coevolve,$C-$counteract
• D
  $A-$source specific,$B-$evolve,$C-$counteract