Role of Soils Engineer:
* Soils engineers address subsurface conditions, such as soil stability, unexpected geology, and underground obstacles.
Evaluation of Other Options:
* A: Survey errors are typically addressed by surveyors.
* C: Archeological findings involve specialists in historical preservation.
* D: Toxic soils are typically handled by environmental engineers.
Verification with PSP Guidelines:
The PSP Study Guide includes subsurface investigations as a key responsibility for geotechnical professionals (Ref: PSP Study Guide, Chapter 1A: Site Conditions).

The cumulative cost baseline typically forms an "S" curve, reflecting slow initial expenditures, accelerating progress during peak activities, and tapering off as the project concludes.
* Option A, B, and D do not represent the characteristic shape of a project's cost curve.
The PSP Study Guide highlights the "S" curve as a standard graphical representation of cumulative project costs over time.