How to select this face?

How can I select this face in the brep using RhinoCommon?

Maybe this can be easily selected.
Might not be so easy to describe.
The more specific question is, how to let this surface participate in the intersection detection of the line alone. At present, it is found that the intersection detection of this surface is a square, not a triangle, there is an extra piece, and the surface on the side of this surface also participates in the intersection calculation, but From the picture, it is impossible for the line we tested to intersect that surface, but in the actual algorithm, it intersects, and it looks like that surface is complete, and it will only intersect when it is complete.