Circles with centers P, Q, and R, having radii 1,2 , and 3 , respectively, lie on the same side of line l and are tangent to l at P^{\prime}, Q^{\prime}, and R^{\prime}, respectively, with Q^{\prime} between P^{\prime} and R^{\prime}. The circle with center Q is externally tangent to each of the other two circles. What is the area of \triangle P Q R ?

**Answer Choices**

A. 0

B. \sqrt{\dfrac{2}{3}}

C. 1

D. \sqrt{6}-\sqrt{2}

E. \sqrt{\dfrac{3}{2}}