Which one of the following is a Dirichlet condition?

• A. \(\int\limits_{{t_1}}^\infty {\left| {x\left( t \right)} \right| < \infty } \)
• B. Signal x(t) must have a finite number of maxima and minima in the expansion interval
• C. x(t) can have an infinite number of finite discontinuities in the expansion interval
• D. x2(t) must be absolutely summable