Hills rise to higher elevation than the land around them, and most. a. are very steep b. are not steep

Most hills are "B. Not steep", since for it to be a hill it needs to be somewhere in between the elevation of flat land and mountainous land, which of course is much higher and usually steeper. 

C, because he has a direct link and profit from the trade. the fastest way by boat to transport those goods is via the panama canal.