JEE Math Practice Question

Let S1 : x2 + y2 = 9 and S2 : (x $$-$$ 2)2 + y2 = 1. Then the locus of center of a variable circle S which touches S1 internally and S2 externally always passes through the points :

1. A.$$\left( {{1 \over 2}, \pm {{\sqrt 5 } \over 2}} \right)$$
2. B.(1, $$\pm$$ 2)
3. C.$$\left( {2, \pm {3 \over 2}} \right)$$
4. D.(0, $$\pm$$ $$\sqrt 3 $$)