The Earth's crust is .

thin
fragile
the outermost layer
all of the above\

I hope this information helps you :)! 

Linnaeus divided nature into three kingdoms: animals, vegetable (or plant),  and minerals. The animal and plant kingdoms were further divided into  smaller, more inclusive categories based on physical characteristics.  As time passed, and knowledge increased, other scientists added to  Linnaeus’ original system.

https://www.coursehero.com/file/12972938/Module-6-Classification-and-Diversity-Review/