Answer:
Antibodies
Explanation:
Specific immune responses are triggered by 'antigens'. Antigens are found on the surface of a pathogen and is used to identify a specific pathogen. Antigens trigger the immune system to release cells that attach themselves to Antigens in order to kill off pathogens. These cells attack Pathogens using <em>antibodies</em>
Answer: Both species must have competed for the same niche. The surviving species is better adapted or adapted better and outcompeted the other.
Explanation:
D. There are three parts of the cell theory and this one is never stated.
