單項(xiàng)選擇題

無(wú)脊椎動(dòng)物神經(jīng)系統(tǒng)的進(jìn)化趨勢(shì)是：（）

A、無(wú)神經(jīng)－神經(jīng)索－梯狀神經(jīng)索－鏈狀狀神經(jīng)索
B、梯狀神經(jīng)索－腹神經(jīng)索－鏈狀神經(jīng)
C、無(wú)神經(jīng)－神經(jīng)網(wǎng)－梯狀神經(jīng)－鏈狀神經(jīng)
D、梯形神經(jīng)－神經(jīng)網(wǎng)－鏈狀神經(jīng)