If$$ a^{2}+b^{2}+c^{2}+84 = 4(a-2b+4c),$$ then $$ \sqrt{ab-bc+ca}$$ is equal to :

A

$$4\sqrt{10}$$

B

$$\sqrt{10}$$

C

$$ 5 \sqrt{10}$$

D

$$2 \sqrt {10}$$