It seems like path b is aimed at getting you ready for the minor if you haven’t studied music seriously before.
From what I can tell from the usual Jacobs requirements, regular Jacobs students use MUS-T 151 as a kind of accelerated introduction, letting them get out of MUS-Z 111 or an even more introductory class, MUS-Z 101, at the cost of adding a few elective credits to their requirements. In this context, it seems like the b path assumes you don’t have even that much background (Jacobs students don’t have any prereq for MUS-T 151, much less a class called Rudiments of Music I).
Personally, my guess is that path b is for media or game design majors with more CS-y or English-y backgrounds who want to do music, but might need a gentler introduction. It doesn’t look like the path that traditional music students do, at all, but for some people it will be the right path.
Since you seem to have serious experience with music, I would opt for MUS-Z 111/Z 211.
According to the AP correspondence chart here (https://admissions.indiana.edu/apply/freshman/ap-exam-credit.html) , knowledge-wise, MUS-Z 111 is roughly equivalent to a 3 or better on the AP music theory exam. As someone who just took AP music theory (and did ok, even though I couldn’t tell you what a seventh chord was going in), you sound like a lot of my classmates at the start of the year. Most of us were band kids, with varied theory backgrounds.
On the other hand, this is Jacobs we’re talking about. The AP exam is a very different experience from intro music theory at a top music school. In other words, MUS-Z 111 will probably not be a cake walk, and there will be outstanding musicians in the classroom with you. I’ll bet you that you’re ready for the course. It just might not be an easy course.