Gaining Charges - To Multiply or Add?

There are a number of different ways to gain charges, by killing enemies, by hitting enemies, etc. And there are multiple sources to increase those odds: the passive tree, certain skills, item effects.

For the life of me, I can't find whether these sources stack multiplicatively or additively.

Here's an example using Flicker Strike:

At 20% quality, Flicker Strike has a 25% chance to gain a Frenzy Charge on Hit.

Let's say we're also wearing a Precursor's Emblem with "10% chance to gain a Frenzy Charge on Hit".

We also have the Sword Mastery allocated which provides "8% chance to gain a Frenzy Charge when you Hit a Unique Enemy".

I make a sword attack with flicker strike against a unique enemy.

Is the chance to gain a Frenzy charge...?

A. 43% [.25 + .10 + .08]

or

B. 37.9% [1 - ((1-.25) * (1-.10) * (1-.08))]

Those %chances are additive effects

As a general rule of thumb, if the wording is the same then it is additive. If the wording changes however slightly, then it is multiplicative. The main exception will be local weapon mods. However, I'm sure there are several examples where that isn't the case, and I'm just not thinking of them now.