- At the hill, carefully, climbed, the hikers.
- The hikers climbed carefully at the hill.
- At the hill climbed the hikers carefully.
- Climbed the hikers at the hill carefully.
The correct sentence structure in English is Place-Adverb-Verb-Subject. The place (at the hill) should come first, followed by the adverb (carefully), the verb (climbed), and finally, the subject (the hikers). The correct option (a) follows this structure.
