What’s the type of damage for a multi-typed weapon damage?

Say i play a level 7 Arcane Trickster Rogue with a Shadow Blade equipped which deals 2d8 Psychic damage. In addition I used Absorb Elements with which i absorbed an Ice Mephit’s Frost Breath on me, which would add 1d6 Cold damage to that attack. Lastly I cast Green-Flame-Blade to finally make my attack which would add 1d8 Fire damage. As the Ice Mephit is resistant to Cold but weak to Fire, I get that the additional damage from Absorb Elements would be halved, but Green-Flame-Blade would be doubled. Now to the sneak Attack:

Beginning at 1st level, you know how to strike subtly and exploit a foe’s distraction. Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must use a finesse or a ranged weapon.

As the Sneak attack inherits the weapon attack’s type, how would i calculate the damage for the sneak attack?

  1. Do I choose which type the sneak attack is?
  2. Is it all types at once, and I count the amount of time an element is resisted or is strong against the enemy? (in this case 1. resistance and 1 vulnerability would neutralise and I’d just take the normal result from my sneak attack die)
  3. Does the damage calculation go by whatever type is more beneficial to a) the attacker or b) the defender?