In a coal-burning power plant, the coal is an example of a system . A. Product
B. Throughout
C. Output
D. Model
E. Input

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

wait any answer choices plz

not sure if this is what you'r looking for eubacteria and archaebacteria