Question

a close relationship between two species that benefits at least one of the species is called...
competition
symbiosis
adaptation
natural selection

Explanation:

• Competition: It is a relationship where species compete for resources like food, space, etc. It doesn't imply a close relationship that benefits at least one species.
• Symbiosis: Symbiosis is defined as a close relationship between two species where at least one species benefits. There are different types of symbiosis - mutualism (both benefit), commensalism (one benefits and the other is neither helped nor harmed), and parasitism (one benefits and the other is harmed).
• Adaptation: Adaptation refers to the process by which an organism becomes better suited to its environment. It is not a relationship between two species.
• Natural selection: Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. It is a mechanism of evolution and not a relationship between two species.

Answer:

B. Symbiosis