windows 7 - Why can't I extend this partition into the unallocated space?

Check out the screenshot below, I want to extend my C partition (where Windows is installed) into the unallocated free space shown. This space was cleared up by shrinking the D partition. I can extend the D partition if I want to, but not the C.

Why not?

Answer

It's because you can only extend a partition if the blank space is directly following it. Your D: partition is in the way.

Perhaps look into a partitioning program like GPartEd.