Let z be a complex variable. For a counterclockwise integration around a unit circle C, centered at origin.
$$\oint_{\text{c}} {\frac{1}{{5{\text{z}} - 4}}{\text{dz}}} = {\text{A}}\pi {\text{i}}$$     the value of A 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