At what velocity does the pacific plate move northwest, relative to the north american plate?

The Pacific Plate moves northwest, relative to the North American Plate about 3.4 cm per year, caused by Shear stress. The fault line that California is on is the San Andraes Fault.

  like australopithecus afarensis; probably the direct ancestor of this group. africa: 5.8 to 4.4 million years ago. 

Ithink the answer is b
not sure