The value of $$\cfrac{a^{2} - (b - c)^{2}}{(a + c )^{2} -b^{2}} + \cfrac{b^{2} - (a - c)^{2}}{(a + b )^{2} -c^{2}} + \cfrac{c^{2} - (a - b)^{2}}{(b + c )^{2} -a^{2}}$$

A

1

B

2

C

-1

D

3