Yes, it is okay. you should never change your hypothesis if it was wrong.
Parasites need a host. If a host tries to get rid of the parasite or kill it, then the parasite either has to leave the body or die.
I say A not sure tho but I did get a grade 5 in biology
Organisms that use the same resources because there may not be enough for all, so it then becomes a competition of who gets it and who doesn't.
Lloyd came up with the idea of Tragedy of the Commons