Answer:
If the barnacle population decreased, it is most likely that the whale population would stay the same.
Step-by-step explanation:
In a commensalistic relationship, one species benefits while the other is unaffected. In this case, barnacles benefit by attaching themselves to the skin of whales, gaining access to a constant source of food and protection. The whales, however, are not directly harmed or helped by the presence of barnacles.
If the barnacle population were to decrease, it would mean fewer barnacles attaching to the whales. This might result in less food availability for some other organisms that rely on barnacles, but it is unlikely to impact the whale population negatively.
It is important to remember that ecosystems are complex, and changes in one species can indirectly affect others. However, in the specific context of the barnacle-whale commensalistic relationship, a decrease in the barnacle population would most likely not cause the whale population to become extinct, decrease, or increase significantly. It would likely stay the same.