In the diagram, the circle with centre X is tangent to the largest circle and passes through the centre of the largest circle. The circles with centres Y and Z are each tangent to the other three circles, as shown. The circle with centre X has radius 1 . The circles with centres Y and Z each have radius r. The value of r is closest to
Answer Choices
A. 0.93
B. 0.91
C. 0.95
D. 0.87
E. 0.89