On a Recent Paper,Maria's Score,transformed to a Z-Score,was +1

Multiple Choice

On a recent paper,Maria's score,transformed to a z-score,was +1.If the cutoff mark is the upper 10% of the class for As,the upper 10% to 20% for Bs,the upper 20% to 30% for Cs,and the upper 30% to 40% for Ds (below 60% being a failure) ,what grade did Maria receive on the quiz?

A) A
B) B
C) C
D) F