Final answer:
The prepositional phrase 'on the table' modifies the noun phrase 'Tony Stark's cookies', providing location information about the cookies in the given sentence.
Step-by-step explanation:
The noun phrase modified by the prepositional phrase 'on the table' in the sentence 'Tony Stark's cookies were on the table a minute ago' is 'Tony Stark's cookies'. This is because the prepositional phrase is giving us additional information about the location of 'Tony Stark's cookies'. In English grammar, prepositional phrases often function as adverbials or adjectives, modifying either verbs or nouns respectively. In this sentence, 'on the table' acts as an adverbial phrase indicating where the cookies were located.