有四座公路桥梁，桥面宽度相同，其中，a桥为钢管混凝土拱桥，b桥为预应力钢筋混凝土简支梁桥，c桥为主跨 300m 的斜拉桥，d桥为主跨 800m 的悬索桥。关于各桥汽车冲击系数的大小，下列说法正确的是：    。

A、<span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"=""><span style="mso-spacerun: yes"></span>d</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"="">桥最大，<span lang="EN-US">b</span>桥最小</span>

B、<span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"="">c</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"="">桥最大，<span lang="EN-US">d</span>桥最小</span>

C、<span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"="">c</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"="">桥最大，<span lang="EN-US">a</span>桥最小<span lang="EN-US"><span style="mso-spacerun: yes"> </span></span></span>

D、<span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"=""><span style="mso-spacerun: yes"></span>b</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; 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"="">桥最大，<span lang="EN-US">d</span>桥最小</span>