In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
--------
Question: Sentence1: Mark was a big fan of nature. Sentence2: He decided to bring trees to the city. Sentence3: He would take a truck load of trees down each week. Sentence4: He would then plant the trees in parks. Sentence5: Over time the trees grew and now Mark is happy!

Answer: Mark

Question: Sentence1: Don showed up for his clarinet lesson. Sentence2: He forgot to bring his music. Sentence3: A teacher told him to play some scales. Sentence4: Don really was not ready for that. Sentence5: After that they played some duets with teacher.

Answer: Don, Teacher

Question: Sentence1: My old boss has an autistic grandson. Sentence2: Paul is five and cannot talk. Sentence3: He was getting treatment but lately has been acting out. Sentence4: Recently the family brought in a dog as a service animal. Sentence5: So far Paul has been calmer.

Answer:
I (myself), Grandson, Dog, Family, Boss