Final answer:
The words 'Selling more than 500 million records' are an example of a participial phrase.
Step-by-step explanation:
The words 'Selling more than 500 million records' in the given sentence are an example of a participial phrase. Participial phrases are phrases that begin with a verb form ending in '-ing' or '-ed', and they function as adjectives in the sentence. In this case, the participial phrase describes Elvis Presley, providing additional information about him.