Compute the Mellin transform to f(t) = t/(t + a) with a > 0.

A、symstz;symsapositive;f=t/(t+a);M=simplify(int(f*t^(z-1),t,0,inf));
B、symstz;symsapositive;f=t/(t+a);M=simplify(Mellin(f*t^(z-1),t,0,inf));
C、symstz;symsapositive;f=t/(t+a);M=simplify(diff(f*t^(z-1),t,0,inf));
D、symstz;symsapositive;f=t/(t+a);M=simplify(iMellin(f*t^(z-1),t,0,inf))