Answer:
none in the sentence
I
happy
to
see
you
Step-by-step explanation:
Although the word 'to' is a preposition, there is no prepositional phrase in the sentence, as it is not acting as such. Prepositional phrases do not have verbs, so in this case the phrase 'to see you' cannot be considered a prepositional phrase, as it is an infinitive clause of reason.