What word Document Type is best for Various Versions of Word

I have Several Customers that Use Microsoft Office and I want to make sure that the Document I send them can be viewed.
But the Unknown factor is What Version of Office Word should I Save My Document as.
One Customer May be Using Word 2010, Another May be Using Word 2016 and another may be using Word 2019.
When Saving my document I noticed that word 2016 is not in the list as save as types.
So What Format Type would make the Receiver Successfully Open My Document.
I am Using Libreoffice 6.4

Basically:

Always create and save your files in LibreOffice and save them in ODF format (ODT, ODS, etc.).
Always keep these files as their source. If you need other formats for distribution to partners, you can open an ODF file and save and distribute another format with ″ Save as… ″.

This way, you always have working files available in your system environment.

See:
https://wiki.documentfoundation.org/Faq/General/118

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If you send your document to someone who uses M$-Word ask them which format is best for them.

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You can also send your file as an .odt because M$ Word claims to be able to read ODF documents. However, when processing alien formats, there are always compatibility problems, often minor but present. So, your question is who do you want to be shown as the culprit? You, as the sender of an approximate .doc(x) document? Or your customers as not having the right tools to handle the document?

If they are just to view the document then use PDF’s. This would eliminate any compatibility issues on their end. In LO use File/export as PDF