Which of the following statements best describes the property of the system T if y1(t)=T[x1(t)], y2(t)= T[x2(t)] implies T[ax1(t-s)+bx2(t-s)]= ay1(t-s)+by2(t-s)()
A.the system is linear B.it is a linear time-invariant system C.the system satisfies the principle of superposition D.the system satisfies additivity and time-invariance