Which is the best description of a strike-slip fault?

Question

Which is the best description of a strike-slip fault?

A. A fault that does not move

B. A fault under compression

C. A fault that forms at a transform boundary

D. A fault under tension

Answer 1

C. A fault that forms at a transform boundary (this is how the San Andreas Fault was born)

Answer 2

Strike is the direction of the fault along the surface of the earth (dip is its angle perpendicular to surface).  Strike slip means it moves laterally (in the direction of the strike) rather than up or down (in the dip direction).  

Tension (pulling apart) and compression (pushing together) involve up and down movement primarily (dip-slip).  Transform boundaries are where blocks slide by each other, so movement is primarily lateral, and the answer is of course C.  

Hope that helps you understand better.