How are synthesis modifiers selected?

Looking at the data-mined modifiers on poedb. They appear to be grouped. How much does that reflect how it works in game ?

My question: Which of the following holds true?

A) Does the game roll for a modifier, and another separate roll for a tier after that ?

B) Or does the game pool all tiers and modifiers together and choses one randomly?

C) Do the modifiers have weights?


I'm trying to estimate how many synthesis attempts it would take to get a single +1 arrow quiver.
In Case A) if it rolled a modifier type first, it would chose 1 out of 65 mod types. The chance to get +1 arrow would be 1:65.

In Case B) it would roll one modifier out of all types and all tiers, making it around a 1:500 pick.

how does it work?