Final answer:
The minimum number of updates you must install is four. To update an Azure Stack Hub Integrated System that's behind by one major version and three hotfixes, only the most recent major update needs to be installed since it contains all previous fixes. The correct answer is D.
Step-by-step explanation:
The minimum number of updates you must install to ensure that your Azure Stack Hub integrated system is running the latest version of the operating system components is four (D).
Since the system is one major version behind the most recent one and there have been three hotfixes released since then, you need to install the latest version and all three hotfixes, totaling four updates.
To update an Azure Stack Hub Integrated System that's behind by one major version and three hotfixes, only the most recent major update needs to be installed since it contains all previous fixes.
When updating an Azure Stack Hub Integrated System that is one major version behind, you would typically need to apply the latest major update first, before applying any subsequent hotfixes. Microsoft's update process for Azure Stack Hub is cumulative, meaning each new update includes all the previous fixes. Therefore, you can usually skip directly to the most recent update. In this scenario, the latest major update would contain the core operating system components you need, along with the hotfixes that were released after that major update. So, to ensure the system is running the latest version with all the appropriate fixes, just one update, the most recent major version, needs to be installed.