Answer:
Jason - subject
had - verb
a birthday party - direct object
at his favorite Mexican restaurant - prepositional phrase
Step-by-step explanation:
The subject of a sentence is the topic, that is, what the sentence is about. The sentence we are analyzing here is talking about Jason, so "Jason" is the subject. The verb "had" is not a linking verb, but an action verb. Its meaning is completed by the direct object that follows. We can ask the verb a question: What did Jason have? A birthday party (direct object). Finally, a prepositional phrase consists of a preposition and complements. In this case, the prepositional phrase "at his favorite Mexican restaurant" provides information as to where the birthday party was thrown.