In the Laurent expansion of $${\text{f}}\left( {\text{z}} \right) = \frac{1}{{\left( {{\text{z}} - 1} \right)\left( {{\text{z}} - 2} \right)}}$$    valid in the region 1 < | z | < 2, the coefficient of $$\frac{1}{{{{\text{z}}^2}}}$$ is

A. -x² + y² + constant B. x² - y² + constant C. x² + y² + constant D. -(x² + y²) + constant

A. 1 + 6i B. 9 - 8i C. 9 + 8i D. 17 + 6i

A. $$2\sqrt 2 + 2{\text{i}}$$ B. $$\frac{{ - 1}}{2} + \frac{{{\text{i}}{{\sqrt 3 }^2}}}{2}$$ C. $$\frac{{\sqrt 3 }}{2} - {\text{i}}\frac{1}{2}$$ D. $$\frac{{\sqrt 3 }}{2} - {\text{i}}\frac{1}{8}$$

A. 2πnj B. 0 C. $$\frac{{\pi {\text{j}}}}{{2\pi }}$$ D. 2πn