Final answer:
AIS position reports fit into one of six time slots that are established every 90 seconds, making option (c) the correct answer.
Step-by-step explanation:
The question concerns the Automatic Identification System (AIS), which is used for the tracking and the exchange of navigation data between vessels and shore-based stations.
AIS stations send periodic position reports, and these reports are slotted for organization and collision avoidance. Each position report from AIS stations fits into one of six time slots established every ninety seconds. Therefore, the correct option is (c) 6, 90.