A
Chain 1: oak trees —> moths —> small birds —> weasels
Chain 2: trees and bushes —> moths —> shrews
B
Voles
C
Since part of shrews’ alimentation are beetles and beetles sometimes eat earthworms, which eat dead leaves, a reduction of the dead leaves will reduce de population of shrews as their food will no longer be as abundant.
D
Level y is small on the first diagram because one organism feeds multiple other ones, while on the other diagram, multiple organisms feed other ones.
Hope it helps !
