A young boy and his talking dog
Answer: their
Explanation: The sentence is addressing car buyers having something, in this instance a choice. When the subject is possessive, you use their. Such as, the car buyers ate <em>their</em> lunch.
Answer:
what did you cook tonight?
Have you finished your homework yet?
My father has gone to the bank.
What were they doing at 9:00 last night
it was snowing when we left the library
