The statement that has a prepositional phase here is:
Early pilots performed stunts
Explanation:
A prepositional phase is usually found in the beginning of the sentence.
The use of the preposition is to draw out the meaning of a noun or a pronoun with respect to another object in the sentence.
The common examples of such phases include Before, After, By, Under, Over and many other such examples which are there to accentuate a relation thus given.
Here, the use is simple.
The word Early is the prepositional phase which makes the connection between pilots and 'stunts' that is different from the one made by the word 'performed' between them.
He finds very painful associated the conk with self-debasement because African American people endure pain to meet white beauty standards. He finds it degrading that they destroy their Bodies to try to look like whites and in the progress .