有一倾斜放置的平面闸门，如图所示。当上下游水位都上升 1m 时（虚线位置）， 闸门上的静水总压力 (  )。

A、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 10.5pt; mso-ascii-font-family: ">变大</span>

B、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 10.5pt; mso-ascii-font-family: ">变小</span>

C、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 10.5pt; mso-ascii-font-family: \'Times New Roman\'; mso-hansi-font-family: \'Times New Roman\'; mso-bidi-font-family: \'Times New Roman\'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">不变</span><span style="FONT-FAMILY: \'Times New Roman\',\'serif\'; FONT-SIZE: 10.5pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体" lang

D、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 10.5pt; mso-ascii-font-family: \'Times New Roman\'; mso-hansi-font-family: \'Times New Roman\'; mso-bidi-font-family: \'Times New Roman\'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">无法确定</span>