The equation of average power of a periodic signal x(t) is given as ___________

• A. \(\sum_{k=0}^{\infty}|c_k|^2\)
• B. \(\sum_{k=-\infty}^{\infty}|c_k|\)
• C. \(\sum_{k=-\infty}^0|c_k|^2\)
• D. \(\sum_{k=-\infty}^{\infty}|c_k|^2\)