The dog and tapeworm both become ill. The dog becomes ill, and the tapeworm benefits. The tapeworm and dog help each other survive. The tapeworm helps the dog survive.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Tapeworms live in the intestines of dogs and absorb nutrients from food the dog eats. Which best describes the outcome of this relationship?
Possibilities:
- The dog and tapeworm both become ill.
- The dog becomes ill, and the tapeworm benefits.
- The tapeworm and dog help each other survive.
- The tapeworm helps the dog survive.

The dog becomes ill, and the tapeworm benefits.