What is the purpose of the cause and effect signal words “as a result”?

to show that Michael’s teacher helped him change the way he viewed the upcoming performance
to show that Michael’s teacher encouraged him even though she didn’t know he was nervous about his performance
to show that Michael’s teacher is the reason that Michael first made the decision to take part in the performance
to show that Michael’s teacher is the cause of the nervousness he feels about taking part in the performance