The amplitude of $\; sin \large\frac{\pi}{5} + i\; \normalsize cos (1-\large\frac{\pi}{5})\;$ is

Question

$(a)\;\large\frac{2\pi}{5}\qquad(b)\;\large\frac{\pi}{5}\qquad(c)\;\large\frac{\pi}{15}\qquad(d)\;\large\frac{\pi}{10}$