3. Let $a, b, c$ be non-zero complex numbers, and $\frac{a}{b}=\frac{b}{c}=\frac{c}{a}$, then the value of $\frac{a+b-c}{a-b+c}$ is (where $w=\frac{-1+\sqrt{3} \mathrm{i}}{2}$ )
A. 1
B. $\pm w$
C. $1, w, w^{2}$
D. $1,-w,-w^{2}$
3. C. $a=b=c$ or $a, b, c$ are $k, k \omega, k \omega^{2}$ respectively.