Take a look at your audience. You can analyze their actions and emotions by keep watching at them most especially those moments where the key points are presented in the performance. From the moment, you can tell whether or not they enjoyed it or bored over watching it.
C is the answer you are looking for. A common idea isn't a moral, the generalization is the Main Idea, but not quite the moral. The thought of the characters almost never have the moral in them. Therefore, C is your answer.
The stranger's interaction with Elisa was a bit awkward since they were not introduced formally and Elisa was a bit professional as she entertains the stranger. On the other hand, Elisa was comfortable with Henry since they have been friends for a while already.
