The practice of grammatical structures in a controlled manner can be done by—

The correct answer is gap-filling grammar exercises.

Explanation:

Controlled practice in language teaching refers to activities where learners are restricted to using specific target language structures, allowing them to focus entirely on accuracy rather than fluency.

1. Gap-filling grammar exercises: These are classic examples of controlled practice because the form and structure are largely provided, requiring the learner to fill in specific grammatical items (e.g., correct verb tenses, prepositions, or articles) within a clear, defined context. This leaves minimal room for error and allows focused practice of specific grammatical rules.

2. Other options:

- Writing paragraphs and essays: This represents free or productive practice, where learners focus on expressing ideas using a wide variety of vocabulary and structures.

- Explaining the use of particular structures: This is a teacher-led explicit instruction or presentation phase, not a practice activity performed by learners.

- Correcting wrong sentences produced by learners: This is a feedback/remedial technique rather than a controlled practice exercise.