Final answer:
The economy is likely the lurking variable between the percentage of the population with a cell phone and the violent crime rate, as it influences both technology access and socio-economic pressures that can affect crime rates. Therefore, the correct option is D. the economy
Step-by-step explanation:
The question is asking about a lurking variable or a hidden factor that might affect both the percentage of the population with a cell phone and the violent crime rate. A lurking variable is an external variable that is not included in the study but can influence the results. Among the given options, the economy would be the most likely lurking variable.
Economic conditions can affect both the ability of individuals to afford cell phones and the crime rate due to socio-economic pressures and opportunities. Factors like income inequality, poverty, and unemployment can both lead to higher crime rates and impact cell phone ownership. Having a strong economy generally allows for better access to technology, while also potentially lowering crime by providing better social support systems and employment opportunities.