Freedmen in the Late Roman World

[Marja]

b) is probably not it, and d) is possible. I've read late Roman sources condemning people for being born poor, let alone being born into slavery. I can't recall the details off the top of my head.

a) might follow if there were fewer slaves, or if there were fewer new slaves being captured. I would suggest looking at some of Scheidel's work:

http://www.princeton.edu/~pswpc/papers/a...eidel.html