Point P is inside equilateral \triangle A B C. Points Q, R, and S are the feet of the perpendiculars from P to \overline{A B}, \overline{B C}, and \overline{C A}, respectively. Given that P Q=1, P R=2, and P S=3, what is A B ?

**Answer Choices**

A. 4

B. 3 \sqrt{3}

C. 6

D. 4 \sqrt{3}

E. 9