- The children play happily in the park.
- The park play the children happily in.
- Happily play the children in the park.
- In the park play the children happily.
The correct sentence structure in English is Place-Subject-Adverb-Verb. The place (in the park) should come first, followed by the subject (the children), the adverb (happily), and finally, the verb (play). The correct option (a) follows this structure.
