Final answer:
The cargo agent, freight forwarder, and the DGR acceptance staff are responsible for ensuring that a package is correctly marked and labeled before accepting the consignment.
Step-by-step explanation:
The parties responsible for checking and ensuring that a package is correctly marked and labeled before accepting the consignment are the cargo agent, the freight forwarder, and the operator's Dangerous Goods Regulations (DGR) acceptance staff. These entities have distinct roles in the logistics chain, with each ensuring that the regulations for the safe and legal transportation of goods are adhered to. The cargo agent typically handles the documentation and initial checks, the freight forwarder arranges for the shipment and may perform additional checks, and the acceptance staff are specifically responsible for confirming that all dangerous goods meet the required standards before a shipment is loaded onto an aircraft or other transportation modes.