Final answer:
The subject of this question is Social Studies, and it is about the two categories in river rescue: swiftwater rescue and floodwater rescue.
Step-by-step explanation:
The subject of this question is Social Studies. It is asking about the two categories in river rescue. River rescues are separated into two categories: swiftwater rescue and floodwater rescue. Swiftwater rescue involves saving people from moving water or rapids, while floodwater rescue deals with rescuing people from flooding situations.