As we know, an adverb is characterized as a word that functions to describe or modify an adjective, verb, or another adverb.
As per the question, <u>the given sentence employs an 'infinitive adverb' i.e. 'to go' because this non-finite verb is functioning to modify the main verb 'allowed' by adding details about it.</u> It answers the question 'allowed what?' by replying 'to go.' It cannot be participle as there is no use of participle in the sentence except for the main verb and hence, options A and B are incorrect. Option D is incorrect as infinitive is not employed as an adjective to modify a noun. Therefore, <u>option C</u> is the correct answer.
