Final answer:
Authorized couriers may open parcels containing classified material for inspection at border crossings. Various detection technologies, including X-ray equipment, are used to reveal the contents of the parcels. These technologies have improved over time and are widely used in ports of entry.
Step-by-step explanation:
In border crossings, authorized couriers may open a parcel containing classified material for inspection. This is done to ensure the safety and security of the country. Inspections at ports of entry involve the use of various detection technologies, such as X-ray equipment, to reveal the contents of packages and vehicles. These technologies have improved over time and are widely used, although their implementation may vary due to factors like cost and availability of qualified staff.