uom conversion factor logic

what the correct way to set uom and conversion factors for an item
for example and item thats 200 each/box, 20 box/case

would it be

A;
each conversion factor 1
box conversion factor 200
case conversion factor 20
or
B:
each conversion factor 1
box conversion factor 200
case conversion factor 4000

Hi,

Option B.

Conversion is relative to Default Stock Unit.

Thanks,

Divyesh Mangroliya