Concept:A tick feeding on a cow is a relationship where the tick benefits and the cow is harmed.
Explanation:This is an example of parasitism.
The tick is the parasite because it attaches to the cow and feeds on its blood.
The cow is the host and suffers from blood loss, irritation, and possible diseases spread by the tick.
Commensalism is not correct because the cow is not unaffected.
Saprophytism is not correct because the tick feeds on a living host, not dead organic matter.
Therefore, the relationship between a tick and a cow is parasitism.
Answer:A. parasitism