Active Partition Manager ((install)) -

Active Partition Manager for Windows - Download it from Uptodown for free

Here is the "magic" that Windows cannot do. Because the unallocated space is currently between C: and D:, C: cannot claim it. active partition manager

While there are many options (EaseUS, MiniTool, AOMEI), one notable tool in this space is (a direct match for our keyword). It offers both a Windows interface and a bootable DOS/Windows PE environment. Active Partition Manager for Windows - Download it