Option 1 -> pleasant weather would facilitate the hike, not hinder it.
Option 2 -> feeble means weak or lacking strength; doesn't aptly describe problematic weather.
Option 3 -> inclement means harsh, severe, or stormy weather conditions.
Option 4 -> favourable weather would help the expedition, not obstruct it.
Hence, Option 3: inclement -> "Put a spanner in" is an idiom meaning to cause problems or disruptions. Only inclement (harsh/severe) weather would create obstacles for a mountaineering team's hike, making it the contextually appropriate choice -> correct