Which part of a pnp-transistor is the buried layer connected to?
The Wikipedia article has a nice illustration of the structure of a typical npn transistor.
The structure of a typical pnp transistor has many similarities.

In particular, both of them have:
A thin surface layer acts as the emitter.
A thin layer buried under the emitter acts as the base.
The substrate -- the bulk material all the way to the bottom surface -- acts as the collector.

As The Photon pointed out,
the vast majority of PNP and NPN transistors are
planar transistors
made entirely of doped silicon.
So any question that asks about "PNP transistor",
you are safe to assume unless the question specifically says otherwise
that it's not talking about the rarely-used heterojunction bipolar transistor.