Explanation:

- The sentence structure is for a general statement, so the word should be in its base form.

- Play: This is the base form of the verb, suitable for instructions or statements. Correct Answer

- Plays: This is the third person singular present tense, not suitable here as "children" is plural.

- Played: This is the past tense, not appropriate since the sentence is in present context.

- Playing: This is the gerund or present participle form, suggesting ongoing action, but not fitting here as the main verb should be in base form.