11. when a supreme court justice agrees with the decision reached by the court in a case, with the reasons why the court made that decision, he or she mas choose to write a a) concurring opinion b) dissenting opinion c) majority opinion d) unanimous opinion

The answer is C) majority opinion.

It isn't A, because a concurring opinion requires the judge(s) to agree with the decision, but not the reason why.
It isn't B, because a dissenting opinion means that the judge(s) doesn't agree with the decision.
It isn't D, because a unanimous decision would require every judge to agree with the same decision.                                                                                        

I hope this helps :)   !