Which of the following is an example of a video file container?

The choice of a video file container refers to a format that is capable of holding different types of data such as video, audio, subtitles, and metadata, all within a single file. The .mp4 format is a widely recognized and used video container. It can compress various types of media efficiently, making it suitable for streaming, downloading, and playback on different devices.

In contrast, the other options represent formats that do not function as video file containers. For example, .raw is typically associated with uncompressed or minimally processed image files. Meanwhile, .txt and .docx are text document formats used for plain text and formatted documents, respectively, neither of which can store video or audio content. Thus, .mp4 stands out specifically as a video file container, capable of encapsulating multiple types of data in a single file, which is key for video production and distribution.