Answer:
D. Allow him to go around obstacles too difficult.
Okay, this is an interesting one but mainly no, most activity's will so you don't push yourself but if you really wanted to you could go for however long you want as long as you are not doing harm to your body, depending if you are on a fitness program there will be limits.
Answer:
humoral immunity
Explanation:
Human** think of it like that
Answer:
c. crust, mantle, outer core, inner core
