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

The correct option is gap-filling grammar exercises.

Explanation:

In language teaching, controlled practice refers to activities that focus strictly on accuracy and targeted grammatical structures. In these activities, learners are guided to use specific structures correctly with minimal room for error.

Why "gap-filling grammar exercises" is correct:
Gap-filling exercises (fill-in-the-blanks) restrict the student's response to specific words or form variations. Because the context is predetermined and limited, students practice the targeted grammatical structure in a highly controlled manner.

Analysis of other options:

1. Correcting wrong sentences produced by learners: This is an assessment or feedback technique rather than a structured practice activity for learners.

2. Writing paragraphs and essays: This represents free or productive practice (free writing) where learners use language creatively with very little control over specific grammatical constraints.

3. Explaining the use of particular structures: This is explicit instruction or presentation of grammar rules, not student practice.