In this case, we know that
actor = exuberant
exuberant = extroverted
Therefore
actor = extroverted
We also know that
[some] shy = actors
So therefore
[some] shy = actors = exuberant = extroverted
A) Some shy people are extroverts.
This must be true, since some shy people are actors and all actors are extroverts. Eliminate.
B) Some shy extroverts are not actors.
This could be true, but it doesn't need to be so it is the correct answer. All shy extroverts could be actors, and we could still fulfill the question that there are some shy actors.
C) Some exuberant people who are actors are shy.
This must be true. If actors = exuberant and some actors = shy, then some shy = exuberant.
D) All people who are not extroverts are not actors.
This must be true. We know that actors = extroverts (and vice versa) so if someone is NOT an extroverts, then they cannot, by definition, be an actor, since an actor must be an extrovert.
E) Some extroverts are shy.
This must be true, since some actors are shy and all actors = extroverts.
IMO the answer is B. This one feels like math...