已知某工程网络计划中工作M的自由时差为3天，总时差为5天，现实际进度影响总工期1天，在其他工作均正常的前提下，工作M的实际进度比计划进度拖延了（     ）天。

A、<font face="宋体"><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="" lang="EN-US">3</span><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="">天</span></font>

B、<font face="宋体"><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="" lang="EN-US">4</span><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="">天 </span></font>

C、<font face="宋体"><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="" lang="EN-US">5</span><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="">天</span></font>

D、<font face="宋体"><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="" lang="EN-US">6</span><span style="FONT-FAMILY: 宋体; FONT-SIZE: 12pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: " times="" new="" roman""="">天</span></font>