Which two factors are most important to the existence of plate ...

[HCHenry]

Which two factors are most important to the existence of plate tectonics on Earth?
 
  A) oxygen in the atmosphere and mantle convection
  B) Earth's liquid outer core and solid inner core
  C) the existence of life and oxygen in the atmosphere
  D) mantle convection and a thin lithosphere

Question 2

According to the Solar Nebula theory, planets
 
  A) should be a common result of star formation.
  B) should be randomly oriented to their star's equator.
  C) will revolve opposite the star's rotation.
  D) should orbit perpendicular to their star's equator.
  E) should be extremely rare.

[mceravolo]

Answer to Question 1

D

Answer to Question 2

A

[HCHenry]

Thanks for the timely response, appreciate it

[scottmt]

Excellent