The Optimum Currency Area theory of Professor Robert Mundell, Columbia University, says that the most relevant criteria for defining a common currency zone is which of the following? Strong system of law within the zone Well defined and effective boarders around the zone High degree of factor (i.e., capital and labor) mobility within the zone Strong economic growth (i.e., high GDP growth) within the zone Strong system of law within the zone Well defined and effective boarders around the zone High degree of factor (i.e., capital and labor) mobility within the zone Strong economic growth (i.e., high GDP growth) within the zone.