Final answer:
Reduced worker activity is an effective administrative control to help road crew workers acclimatize to working in the heat, by slowly increasing their exposure time.
Step-by-step explanation:
Rick, being the supervisor of a road crew working on highway resurfacing, needs to implement effective administrative controls to help his workers acclimatize to working in the heat. One possible control is a 'heat stress assessment', which helps to identify the risks and necessary interventions. However, to directly help workers acclimatize, reduced worker activity might be the most effective method. This could involve gradually increasing the length of time workers are exposed to the heat allowing their bodies to adapt. Additionally, providing mandatory water breaks can ensure hydration and help in acclimatization. Although not an administrative control, cooling vests can complement these procedures by offering physical relief from the heat.