The underlined phrase that exemplifies a prepositional phrase would be:
B). with his friends
'Prepositional Phrases' are characterized as the expressions or phrases that involve a preposition accompanied by its object and some or any modifier words to modify the object.
These phrases function to display the association or relationship between a noun and other components of the sentence. They also act to add a modification to a noun or the verb present in the sentence.
In the given sentence, the phrase 'with his friends' is the prepositional phrase as it begins with a preposition 'with' followed by the object of the preposition i.e. 'friends' and its modifier 'his.'
How I would write it: In order for happiness to be present in ones life, one must be capable of supporting themselves, and doing acts of serviced for others.