The correct answer is Option (2) - 2 : 1.
Old ratio = 6:3:2 (A, B and C)
C retires.
In the absence of any information regarding profit sharing ratio in which the remaining partners acquire the share of retiring/deceased partner, it is assumed that they will acquire it in the old profit sharing ratio and so share the future profits in their old ratio.
So, old ratio of A & B = 6:3
New ratio is also same i.e. 6:3 or 2:1. | 
