Chris,
Thanks for sharing your feedback. Currently, we support the below types and formats 
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Image (supports .png, .jpg, .jpeg and .svg format)
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Document (supports .xls, .doc, .csv, .pdf format)
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Video (supports .mp4, .3gp, .flv, .wmv format)
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Audio (supports .mp3, .wav, .aac, .amr, .m4a format)
You can upload up to 5 files by increasing the number of files counter 
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Attached screenshot below for reference 
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More details on this Link
This covers the most commonly used file types and formats and helps the survey respondent to choose from different options.
However, we love 
to add new extensions and request you to share those here so that we could pass this to our product team.
Until then Stay Safe
.
