During trace cutting for a proposed road alignment in difficult terrain, deviation from the originally set centerline may be permitted in areas characterized by which of the following conditions?

Introduction / Context:
In preliminary route location, a trace cut is made to physically mark and inspect the proposed alignment. In rugged or environmentally sensitive areas, minor deviations may be needed to avoid unsafe or impractical sections while maintaining overall design intent.

Given Data / Assumptions:

• Alignment passes through problematic zones.
• Objective is to allow practical deviation where necessary for stability and safety.
• Minimal deviation is preferred to preserve designed geometry.

Concept / Approach:
Among the listed conditions, landslide-prone stretches pose immediate geotechnical hazards that justify deviating the trace to safer ground. While sand dunes and wildlife dens may also influence alignment refinements, conventional exam keys typically emphasize landslides as the definitive reason to permit deviation at the trace-cut stage due to acute instability risks.

Step-by-Step Solution:
Identify high-risk ground conditions along the trace.Prioritize geotechnical safety: landslides warrant immediate avoidance.Permissible deviation: re-route locally to stable terrain and re-tie into design alignment.

Verification / Alternative check:
Field manuals recommend bypassing unstable slopes and recent slide debris, then re-establishing control points, especially in hill roads where slope failures are common.

Why Other Options Are Wrong:

• Sand dunes: alignment may be adjusted, but stabilization techniques or dune-crossing design often suffice without major trace deviation in exam context.
• Dens: environmental mitigation can be applied; not the standard singular reason in MCQ keys.
• None of these: incorrect because landslides clearly justify deviation.

Common Pitfalls:

• Underestimating slope instability during monsoon; failing to check recent slide scars.
• Over-deviating and losing geometric control; deviations should be minimal.

Final Answer:
Land slides