Which is the contrapositive of this conditional? If a triangle is obtuse, then it has exactly one obtuse angle.

A. If a triangle is not obtuse, then it does not have exactly one obtuse angle.
B. If a triangle does not have exactly one obtuse angle then it is not obtuse.
C. If a triangle has exactly one obtuse angle, then the triangle is obtuse.
D. If a triangle is obtuse, then it does not have exactly one obtuse angle.