In the diagram, \triangle P Q R is right-angled at R, P R=12, and Q R=16. Also, M is the midpoint of P Q and N is the point on Q R so that M N is perpendicular to P Q. The area of \triangle P N R is
Answer Choices
A. 21
B. 17.5
C. 36
D. 16
E. 21.5