Final answer:
The subject pronoun in the provided sentence is 'he,' and the object pronoun is 'us,' making the correct answer a) he, us.
Step-by-step explanation:
In the sentence “Raul was very tired after his long flight, but he told us all about his trip to Argentina,” the subject pronoun is 'he' and the object pronoun is 'us.' The subject pronoun 'he' refers to Raul and is the one doing the action of telling, while the object pronoun 'us' receives the action of the verb 'told.' Therefore, the correct answer is a) he, us. Pronouns have three cases: subjective, objective, and possessive. The subjective case is used for the subject of a sentence, the objective case for the object of a sentence or preposition, and the possessive case shows ownership.