Final answer:
b) Scuba diving
You should not take up scuba diving unless you know how to swim, due to the need to manage buoyancy, pressure, and risks associated with pressurized gases in the body. Diving without swimming knowledge can lead to accidents, compounded by misconceptions about how drowning looks. Non-swimmers should avoid scuba diving and ensure to understand water safety signs and the impact of body orientation in water.
Step-by-step explanation:
An activity you shouldn't take up unless you know how to swim is b) Scuba diving. Scuba diving requires a good understanding of buoyancy, pressure equalization, and the management of time spent underwater to prevent risks associated with pressurized gases in the body. Not knowing how to swim could lead to panic or inability to manage these factors, which could result in serious injury or drowning.
It's important for individuals to recognize signage like "no diving" as diving in shallow water can cause severe injuries, particularly to the nervous system. When someone doesn't know how to swim, they're also more susceptible to accidents because myths often misinform the public about drowning signs. For instance, a drowning person may not be able to shout for help or wave their arms but rather might silently struggle below the surface.
Through experiments, we can understand the impact of body orientation in water. For example, hitting water with the full palm simulates a belly flop, which causes a larger and more dangerous impact than entering the water with a diving hand (fingers first). Therefore, for safety, non-swimmers should avoid activities like scuba diving, which require controlled diving and swimming abilities.