Infinite number of bricks are placed one over the other as shown in the figure. Each succeeding brick having half the length and breadth of its preceding brick and the mass of each succeeding bricks being `(1//4)^(th)` of the preceding one. Taking `'O'` as the origin, the `x` coordinate of centre of mass of the system of bricks is at

Options

A. `-(a)/(7)`
B. `(3a)/(7)`
C. `-(3a)/(7)`
D. `-(2a)/(7)`