Final answer:
Rip currents and tidal currents are hazardous to swimmers; rip currents can pull them out to sea, while tidal currents cause dangerous water motion and depth changes.
Step-by-step explanation:
The types of near-shore currents that can be hazardous to swimmers include b. Rip currents, which can pull swimmers away from the shore, and c. Tidal currents, which are powerful flows of water that move toward and away from the shore due to the gravitational pull of the moon and sun. Although longshore currents and channel currents are significant in their own right, they are generally less directly hazardous to swimmers than rip and tidal currents.
Rip currents are particularly notorious for their ability to catch swimmers unaware, dragging them out to deeper waters. Safety campaigns often emphasize the importance of understanding and recognizing rip currents to reduce drowning incidents. Tidal currents, on the other hand, can change the depth of the water dramatically and create hazardous conditions especially in areas like inlets and estuaries where water flows in and out with the tides.