Answer:
Variation can be acted on by natural selection.
Step-by-step explanation:
Variation are the difference that exist in the organism in terms of the body size and can be acted upon by natural selection.
Natural selection could act on the owl body size, favor the selection of owl with small body size especially when resources available are limited and can only sustain small number of individuals leading to availability of owl with small body size in such area and a gradual reduction in the number of owl with large body size.