根据《招标投标法》，招标人对已发出的招标文件进行修改的，应当在招标文件要求提交投标文件截止时间至少（　）日前，通知所有招标文件收受人。

A、<p><span style="font-family: \'Microsoft YaHei\'; font-size: 13px; ">15</span></p>

B、<p><span style="font-family: \'Microsoft YaHei\'; font-size: 13px; ">20</span></p>

C、<p><span style="font-family: \'Microsoft YaHei\'; font-size: 13px; ">30</span></p>

D、<p><span style="font-family: \'Microsoft YaHei\'; font-size: 13px; ">60</span></p>

A、<p><span style="font-family: 'Microsoft YaHei'; font-size: 13px; ">15</span></p>

B、<p><span style="font-family: 'Microsoft YaHei'; font-size: 13px; ">20</span></p>

C、<p><span style="font-family: 'Microsoft YaHei'; font-size: 13px; ">30</span></p>

D、<p><span style="font-family: 'Microsoft YaHei'; font-size: 13px; ">60</span></p>