The complex exponential power form of Fourier series of x(t) is: $$x\left( t \right) = \sum\nolimits_{k = - \infty }^\infty {{a_k}.{e^{j\frac{{2\pi }}{{{T_0}}}.kt}}} $$
If $$x\left( t \right) = \sum\nolimits_{b = - \infty }^\infty \delta \left( {t - b} \right),$$     then the value of ak is:

A. 1 - (-1)^k

B. 1 + (-1)^k

C. 1

D. -1

Answer: Option C