Respuesta :
The transition word furthermore signals to the reader that the writer wants to share additional information about what children who take music lessons experience (B).
Simply by looking at the word furthermore, you can guess that it serves the purpose of introducing additional information to defend one same argument: you have further + more.
In this context, the author is adding the point about learning the power of verbal & nonverbal communication to their previous argument, which was how group music lessons teach children how to work in harmony. These two elements defend the same argument: that learning how to play a musical instrument at a young age helps with social skills.
Synonyms of furthermore include moreover, what's more, and besides.