1. P (because the tick is benefited but the dog isn't.)
2. M (because both organisms are benefited.)
3. P (the tapeworm is benefited but the student isn't.)
4. C (because the bird's nest is benefited and the tree is not harmed)
5. C (the hermit crab needs the sea anemones and the sea anemones is not harmed)
But yeah I gave you a few examples of (P, M, and C), so you should figure it out now.
6. C
7. P
8. M
