一家电脑配件零售商决定在其插播视频广告系列中添加一个新的 640x480 像素的 MP4 视频广告展示位置。为了将该视频格式和分辨率选项添加到自己的广告系列中，他们应当在 Campaign Manager 360 中完成下面哪项操作？

To add a new video format and resolution like a 640x480 MP4 to an in-stream video campaign in Campaign Manager 360, the retailer must enable the specific option in the transcoding list. Campaign Manager 360 transcodes uploaded video assets into various formats and resolutions to ensure compatibility across different publishers and devices. Enabling the specific 640x480 MP4 option ensures that this particular rendition is generated and available for serving. Simply uploading the video file is insufficient, as it won't automatically create all necessary renditions. Submitting a new tag to the publisher is a later step, not the action to enable a new format within CM360. Enabling all transcoding options is generally unnecessary and can lead to excessive file generation, increasing storage and processing, when only a specific format is required.