DISCUSSION: Only lines 13-17 mention “West Coast Cool”.
All we really know is that Davis’ innovations in New York laid the foundations for “West Coast Cool”.
Davis himself did not play “West Coast Cool”. He had moved on to other things (lines 18-19).
___________
- Lines 18-19 tell us Davis didn’t stick with “West Coast Cool”, so it’s doubtful he popularized it.
- This is more like Davis’ work from lines 24-27.
- This is doubtful. Davis and a small group of people laid the basis for “West Coast Cool”.
- This also describes Davis’ work from the third paragraph. When Davis had moved on from his work that led to “West Coast Cool”, he experimented with more chord changes.
(lines 20-22). - CORRECT. Specifically, Davis’ innovations in a New York City Apartment led to West Coast Cool. (lines 12 and 15-17)

Re: option C.
I don’t think “This is doubtful. Davis and a small group of people laid the basis for “West Coast Cool” is it.
A small group of band leaders can create innovations even when the vast majority of the band is not involved, and where the band (ensemble) is large.
I think the innovations involved “ensemble playing as much as or even more than solos” but that a large amount of ensemble playing does not imply the ensemble playing was large. The option equivocates ensemble to mean both a group of musicians (an ensemble of musicians) and playing together in a piece (ensemble playing). This leads to the flawed reasoning more ensemble playing = larger ensemble.
The difference here is between an ensemble and a LARGE ensemble. Davis has an ensemble of musicians that met in a NYC apartment. By definition that wouldn’t be large. Usually you couldn’t fit more than say 6-8 people playing instruments into an apartment.
It’s of course possible that these innovations were later taken up mainly by large ensembles. But we have no evidence for that, and meanwhile the innovations were developed by a small ensemble. That’s why I said C is “doubtful”. Not impossible, just doubtful. No evidence for, some evidence against.