Which of the following do the United States and Canada have in common? Same governing body
Similar climates
World's longest unfortified border
First American populations

its the world's longest unfortified border :))

d is the logical answer but im not a 100% sure

true. earthquakes are felt whenever there is a slip around a fault in the rocks below the earth. this reorientation of faults create sesmic waves and is known as earthquake, the severity of which is measured in richter scale. these are more prominent in hilly regions as the rocks usually form faults to balance the pressures on it.