Hi @Jee wo ,
In order to do this natively the unallocated space must be adjacent, i.e. next to the drive you want to extend.
One method is to use third-party software which may offer the option to extend right away. With the Disk Management you would be required to delete the "New Volume 318.10GB) volume that is on the right of your Unallocated space to be able to extend your C-disk.
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