DE Beastmasters/PfP interaction

Okay, branching off on a tangent from another forum....

I am seeing (here and elsewhere in person) a few different views regarding Power from Pain interactions.
I think everyone agrees that by RAW Pain tokens affect any unit they are applied to, and if not...well, we are just going to assume you do for this thread.

With beastmaster units, we have a core model (beastmasters) that have the PfP rule.
Each beastmaster may be attended by various beasties in various numbers..doesn't matter, except none of said beasts have PfP.

As discussed in other places, and encountered directly elsewhere, I have heard 4 different takes on the unit and rule interaction. (for this discussion, we are assuming the beastmasters ARE bringing their friends to the party, and not flying solo..as it would be silly not to).

the arguments follow these 4 posits;
a) the unit is a group of beastmasters that have beasts in the vein of Fen Wolves attached to SW characters as wargear.

b) the unit is a group of beastmasters that have beasts in the vein of Drones attached to crisis suits (subtle, but significant rules difference between the two)

c) the unit is solely a whole, and can in NO WAY be segregated in any phase, hence cannot garner tokens (by their own actions) due to the rule lacking on the whole unit.

d) the unit is solely a whole, but can be differentiated if it can be proven the beastmasters themselves are responsible for final kills as they have the rule the unit generates a token.

I am in camp C by RAW. I will defend that premise here when challenged, but want to hear where other people fall AND WHY (or if there are other positions I've missed that fall outside these 4 base arguments).

the base rule for PfP states that a 'unit' with this rule, when successful at wiping out a non-vehicle unit, gains a Pain Token.