Answer:
The crust is not the thickest layer of earth
:)
I think the relationship is Commensalism ( relationship between two organisms in which one benefits and the other does not benefit nor is harmed ) because the bird benefits and the cow does not benefit nor is harmed. Hope this helped ☺
The dissolved sugars produced in the leaves of a maple tree move to the roots through the<em><u> phloem</u></em>. It is a tissue that transports nutrients to where it is needed
Hope it helps:)