What is the thick layer of bone surrounding the medullary cavity composed of?

Which of the following is most important in making the typical seed more resistant to adverse conditions than the typical spore? a) a different type of sporopollenin b) an internal reservoir of liquid water c) integument(s) d) ability to be dispersed e) waxy cuticle

Which beat describes the brain stem

Answer now! good pts and a brainliest potatoes are what im like a potatoe irdk have a good day