描述线性离散系统常用的数学模型是（     ）。

A、<span style="font-size: 16px;font-family: 宋体">差分方程</span><span style="font-size: 16px;font-family: &#39;Times New Roman&#39;, serif"> &nbsp; &nbsp;&nbsp;</span>

B、<span style="font-size: 12pt; font-family: 宋体;">传递函数</span>

C、<span style="font-size: 16px;font-family: 宋体">脉冲传递函数</span><span style="font-size: 16px;font-family: &#39;Times New Roman&#39;, serif">&nbsp; &nbsp;&nbsp;</span>

D、<span style="font-size: 16px;font-family: 宋体">微分方程</span><span style="font-size: 16px;font-family: &#39;Times New Roman&#39;, serif">&nbsp; &nbsp;&nbsp;</span>

E、<span style="font-size: 12pt; font-family: 宋体;">离散状态空间方程</span>