The word, 'insisted' conveys a command that something be done. In such cases, the person who 'insisted' ('coach' in the given sentence) is different from the third person who performs the action ('Ronaldo' in the given sentence). The action ('play') performed by the third person (by 'Ronaldo') is said to be in subjunctive mood. Subjunctive mood usually expresses something that one wishes for, or a hypothetical rather than an actual situation. The verb in subjunctive mood is always in present tense without the letter 's'. Hence, the correct answer is 'play' as given in option A.
Given the format of the verb in subjunctive mood (i.e. present tense without the letter 's'), options B and C are incorrect.
Option D is incorrect as option A is the correct answer.