Final answer:
Crime displacement likely explains the increase in a neighboring town's crime rate due to the preventative measures taken in the first town, aligning with the routine activity theory.
Step-by-step explanation:
Gary, the town mayor, is utilizing situational choice theory to reduce crime by improving environmental factors. This approach has led to a crime rate decrease in his town. However, the neighboring town's crime rate increase could potentially exemplify the concept of crime displacement, where crime moves from one area to another due to increased prevention measures in the initial area. Although the answer is not explicitly provided in the question, the scenario suggests a shift of opportunities for crime rather than a crime emergence due to social or psychological factors implied by the other theories mentioned, such as Strain theory, Differential association, or Labeling theory. Routine activity theory may provide an explanation for this scenario, as it suggests that the increase in preventative measures in one area may alter criminal opportunities, causing criminals to move to areas with fewer barriers against their activities.