(Spanned Volume). Just know you are gambling with your data.
Use MBR for boot drives under 2TB. Use GPT for everything else. Leave Dynamic disks for legacy servers and tech historians. convert to dynamic disk vs mbr
A is a separate form of volume management that uses a database (the Logical Disk Manager ) to track information about its volumes. It can use either the MBR or GPT partition style as its underlying base. (Spanned Volume)
For most people, the safe advice is don’t click it . But that answer isn't very helpful if you're running out of drive letters or trying to set up a RAID array at home. Use GPT for everything else
You are on an older version of Windows (7, XP, Vista) that doesn't support GPT, but you need to combine multiple physical hard drives into one giant "virtual" drive.
This is a comprehensive guide regarding the differences, pros, cons, and conversion processes between Basic/MBR disks and Dynamic Disks.