Welcome, Shingo-cria!
The important thing to remember here is that every time a unit crosses a boundary between spaces, it uses one movement point. A fighter taking off from one island and landing on another island in an adjacent sea zone will use three movement points – one to enter the sea zone that the original island is in, one to move to the next sea zone, and one to move to the destination island in that sea zone.
In a similar example, if that fighter were doing the same thing except taking off from a carrier in the original sea zone instead of an island, it would use only two movement points because it’s already in the origination sea zone rather than on an island within it. Since it’s starting from the sea zone rather than the island, it only crosses two space boundaries during its movement.
As a result, only the purple line is correct in your example for normal air movement. The others are all incorrect.
However, the Island Air Bases National Advantage allows you to basically treat islands like stationary aircraft carriers. It does not cost one movement point to move into the sea zone surrounding them. Using that Advantage, the green and yellow lines are correct, and all of the others are incorrect.
I hope this helps.