Two circles of same radii r and centres O and O' touch each other at P as shown in Fig. 10.91. If O O' is produced to meet the cirele C (O', r) at A and AT is a tangent to the circle C (O,r) such that O'Q
AT. Then AO : AO' =
(a) 3/2
(b) 2
(c) 3
(d) 1/4