6. In the plane of isosceles $\triangle A B C(A B=A C \neq B C)$, there is a point $P$ such that $\triangle P A B, \triangle P B C, \triangle P A C$ are all isosceles triangles. Then the number of points satisfying this condition is ( ).
(A) 1
(B) 3
(C) 6
(D) 7
$6 . C$