Nothing of the options given.
I require characters to spend some time (mention here and there as appropriate) with something, which could be related to learning a new skill/ability, but there is no formal training required or anything. For example, when picking up a new knowledge skill, some time in the local library might serve. Often adventuring is enough explanation, too, especially for raising existing abilities, which are used regularily. In most cases, the players know what they want to learn next level and can do that during the current level at some point or another. Usually it's then a day off, if the characters have collected enough XP to level up, to reflect on what they have learned and actually gain the level. It's neither *poof* there you are, nor a trainer required to show you how things are done.
Bye
Thanee