While on a walk near lake you see a man floating on the surface without movement. People nearby describe his fall from the bridge.
Wrong. The jump into unknown water is not very smart, but it is your duty to call for help at least.
Wrong. At first you have to check, if it is safe to enter the lake.
Correct. Non-professional has to think about his safety. The most safe possibility is a rescue without the need to enter the water. If a rescuer can not act, he calls for help immediately.