Explanation

MP4 (MPEG-4 Part 14) is a widely used container format for transmitting streaming videos online.

It supports various codecs, including H.264, which is known for its efficient compression and compatibility with most devices. 

Why other options are incorrect:

AVI (Audio Video Interleave):

While AVI is a common video format, it's not as optimized for streaming as MP4.

It can be larger and less efficient for online delivery. 

WMA (Windows Media Audio):

WMA is primarily an audio format, not designed for video streaming. 

WAV:

WAV is a pure audio format used for high-quality recordings.

It's not suitable for streaming video.