The answer is Scenario (b) (i.e. Technician won't apply).
This is because
>For moves with variable base power, Technician will only apply if the base power is 60 or less when used. Thus, Pursuit will not get a Technician boost if the opposing Pokémon switches and Pursuit's base power doubles to 80. Similarly, if a move like Avalanche is used by a Pokémon previously damaged in the same turn, which doubles Avalanche's base power to 120, then Technician will not be applied.
I would count Acrobatics as a move with variable base power, much like pursuit. As such, it will only be boosted by Technician if the user is holding an item.