Answer: A, his friend
Step-by-step explanation:
The sentence "Schütteln Sie bitte nicht" translates to "Please don't shake" in English, and since it would seem strange for Finn to say that to their parents, classmates, or teacher, it would leave only the friend left. Here is a situation where it would make sense: Finn and their friend are in a haunted house, and the friend is anxious and a little afraid.