What is the value of $$a^{2} + b^{2} + c^{2} - 2ab - 2bc + 2ca$$?

A

$$(a - b - c)^{2} $$

B

$$(a + b - c)^{2} $$

C

$$(a + b + c)^{2} $$

D

$$(a - b + c)^{2} $$