Continental drift speed is 1x 10^-9 m/s. this is equivalent to a speed of

Continental drift is one of the earliest ways that geologists thought continents moved over time. It is believed in this theory that the Earth’s movement of the continents are relative to each other.  This idea was subsumed by the plate tectonics theory. Now, what is the speed of the continental drift?  

Continental drift speed is 1x 10^-9 m/s.
This is equivalent to a speed of:
 1 x 10 ^-9 m/s
  = 1 x 0. 000 000 000 1 m/s
  = 0. 000 000 000 1 m/s  

Answer:   [a]:   "slate" .