The third option "Rhyolitic" would be your answer.
They are sandwiched between two layers of heads. Recall that the heads are hydrophilic therefore they will always be on the outside and the tails are hydrophobi therefore they willl always be away from water, there fore sandwiched. I'm a bio major, hope I helped :)
This depends a lot on the area in which the vacant lot is located, but in general it can be assumed that many plans would come up through cracks in the concrete.
