10. If $a, b, c$ are any three rational numbers, then among the following four expressions, the one equal to $|a-b+c|+2017$ is ( ).
(A) $|a+b-c|-2017$.
(B) $|b-c-a|+2017$.
(C) $|c-a+b|-2017$.
(D) $|c-a-b|+2017$.

Answer: B.
Solution: Since $|a-b+c|+2017=|-(a-b+c)|+2017$
$$
=|-a+b-c|+2017=|b-c-a|+2017 \text {. }
$$

Therefore, the correct choice is B.