Descent below MDA -- what would you do?

"Steven P. McNicoll" wrote:
From the Pilot/Controller Glossary:
SURFACE AREA- The airspace contained by the lateral boundary of the Class B,
C, D, or E airspace designated for an airport that begins at the surface and
extends upward.

I probably should know this, but now that I (re-)read the above, I see that
there's several ways to parse that sentence with respect to B and C
airspace:

1) Only the inner cylinder that touches the surface is the surface area,
i.e. SVFR is not available in the outer rings of B/C airspace.

2) The boundaries of the surface area are exactly the same (vertical and
lateral) as the B/C airspace. This is what I had always assumed.

3) The surface area includes all the airspace from the edge of the
outermost ring projected down to the surface. This would be extremely
illogical, but it is one possible parsing.

Which is correct?

Is there such a thing as B, C, or D airspace in the US which is not
"designated for an airport"?