When can ATC issue a Standard Terminal Arrival Route (STAR)?

A Standard Terminal Arrival Route (STAR) is designed to provide a standardized route for aircraft to descend and approach an airport, which enhances the efficiency and safety of air traffic management. The correct reasoning for when ATC issues a STAR is based on operational needs and circumstances.

ATC will issue a STAR when they deem it appropriate based on factors such as the current traffic conditions, weather, and the specific characteristics of the arrival aircraft. This allows ATC to maintain safe separation between aircraft, manage airspace efficiently, and streamline the flow of aircraft into busy terminal areas.

The other options don't adequately represent the conditions under which a STAR is issued. For example, merely denying a pilot's request does not trigger a STAR, and it isn’t automatically applied to all arrivals since ATC has the discretion to utilize different procedures based on situational needs. Moreover, issuing a STAR solely during peak traffic times overlooks the importance of flexibility in air traffic management, as these routes can be used whenever circumstances warrant their application.