In a regular polygon of `n` sides, each corner is at a distance `r` from the centre. Identical charges of magnitude `Q` are placed at `(n-1)` corners. The field at the centre is
A. `d Q/(r^(2))`
B. `(n-1) k Q/(r^(2))`
C. `n/(n-1) kQ/(r^(2))`
D. `(n-1)/n k Q/(r^(2))`
