a)       Connecting a wire from the positive terminal of a 9V battery to a 100kOhm resistor, connecting the other end of the resistor to a light emitting diode, then connecting the other end to the negative terminal of the 9V battery.

connecting two batteries in parallel and leaving for a long time

connecting the terminals of a battery with a wire

connecting wires directly to a 240 V AC source such as a powerpoint