我省苏北有些滩涂地区的土壤被称之为“盐碱地”，当地农民常用引进内河淡水浸泡再排水的方法改良土壤。若以土壤pH为纵坐标，9x;R;p1o2{,K+s3]4y:E-_(b8`-y
浸泡水的次数（m）为横坐标，下列能正确表示土壤pH变化的图是(q7o.z4^)M,h9x;R;p1o2{,K+s3]4y:E-_(b8`-y
A．
9x;R;p1o2{,K+s3]4y:E-_(b8`-y
B．
9x;R;p1o2{,K+s3]4y:E-_(b8`-y
C．
9x;R;p1o2{,K+s3]4y:E-_(b8`-y
D．
9x;R;p1o2{,K+s3]4y:E-_(b8`-y