This question tests knowledge of the specific functions carried out by the ports authority, as distinct from the functions of other agencies that also operate at seaports.
The ports authority is responsible for developing and running port facilities that support the movement and temporary storage of cargo passing through the port. Among its core functions is providing warehousing services, meaning it builds and manages sheds, silos, and storage areas where imported or exported goods can be kept safely while they await clearance, onward transport, or collection by owners.
The remaining options belong to other agencies rather than the ports authority. Collecting import duties and checking the activities of smugglers are functions carried out by the customs service, whose job is to assess and collect government revenue on goods crossing the border and to prevent the illegal movement of goods. Enforcing general law and order in harbours falls to the police and other security agencies operating at the port, not to the ports authority itself, whose role is essentially the commercial and operational management of port facilities.
When a question lists port-related duties, separate the ports authority's role, providing physical infrastructure and services like warehousing, berthing, and cargo handling, from the customs and security functions of duty collection, anti-smuggling checks, and policing.