The microscopic observations of cells form the basis of the cell theory and the idea that all living things are composed of cells; cells are the structural and functional unit of living things.
The right option is the second option, which states "<span>fur color that closely matches the eucalyptus bark color</span>". Change is in the fur color of Koala's to match the bark color of eucalyptus tree is a structural adaptation that fits them for their habitat as tree-dwellers.
I am like 99% sure its organ , try that and see if it works :)
Serious systemic fungal infections and parasitic infections usually only develop in individuals who are immunocompromised. These individuals have a weak immune system. The body cannot respond quickly to infections since their immunity is not very well developed.