Final answer:
The activity that is applicable to the final stage of exporting is modifying advertising and public relations to suit individual markets.
Step-by-step explanation:
The activity that is applicable to the final stage of exporting is The firm modifies advertising and public relations to suit individual markets (Option C). This is because in the final stage of exporting, companies need to adapt their marketing strategies to appeal to customers in different markets. By modifying their advertising and public relations efforts, firms can effectively communicate with their target audience and increase their chances of success in the export market.