Respuesta :
I'm not sure what the underlined phrase is, but if it is "the possibility of black holes", then the answer is "direct object". "Many scientists" is the subject, there is no "predicate noun" because there is no linking verb here, there are no adverbs in this sentence, nor adjectives, and the object of a preposition would be "black holes", because it follows a preposition OF.
SOS
Answer:
PHRASE: prepositional
FUNCTION: adjective
hope this helps!!