I’m really confused about which one of these flaps is used
Before answering that question we have to understand why there are so many kind of flaps. The main difference among the flaps in your picture is their complexity and efficiency.
Regarding complexity, just compare the actuating mechanisms of a simple plain flap in respect to a double-slotted flap:
(Plain flap, source)
(Double-slotted flap, source)
A plain flap just need a couple of hinges to work, while a double-slotted flaps need several linkages, actuators and tracks to move. Complexity obviously implies also an higher price and more maintenance.
Regarding efficiency, said "$∆C_l$" the gain in lift coefficient that the flap needs to supply, an efficient flap generate less drag than an inefficient one:
(Polar comparison for different kinds of flaps, source)
Looking at the plot on the right, just say that for our approaching manoeuvre we need a $C_l$ of 2: following the plot we see that a plain flap generates a relevant drag coefficient of 0.1 while a slotted flap generates only 0.05 i.e. half of it. Looking instead at the plot on the left, you can see that a plain flap reach that $C_l$ of 2 at some 15° angle of attack, dangerously close to the stall region; a slotted flap reaches the same lift coefficient at some 5° with a good margin to stall.
Summarising, going from top to bottom, we encounter flaps with growing complexity but better efficiency: a plain flap is easy to manufacture, maintain and actuate than a double (or even triple) slotted flap. Anyway the latter is more efficient and possibly safer.
which flap would a big airliner (like A320 use please)?
Typically you'll find a plain flap on GA airplanes and a double-slotted flap on a jetliner.