What causes thermal convection that drives plate motion?

The kind of fertilization found in the majority of aquatic animals is (internal or external) fertilization.

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins

18. over time, how do sand dunes tend to migrate? a. perpendicular to the movement of the wind b. in the same direction as the wind blows c. toward the wind d. in random directions