what is the primary factor that determines whether a trait is advantageous in terms of natural selection?

explanation:

they can be good for the ecosystem

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.