@Maharram Najafov - Thanks for the question and using MS Q&A platform.
The minimum number of retention policies that you should use to meet the retention requirement for the users' Microsoft 365 data depends on your organization's specific needs and requirements. However, you can create a single retention policy that applies to all locations and content types, or you can create multiple retention policies that apply to specific locations and content types. So, the answer to your question is A. 1, but it may vary depending on your organization's specific needs and requirements.
You can refer to the following documentation for more information on creating and configuring retention policies in Microsoft 365: Create and configure retention policies.
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