Your picture is a good one and would have scored well in the "centered" challenge, but I fear it will not do as well here as the DOF is not well represented.
I find this a rather dull subject and an odd choice for this challenge. It isn't displaying deep depth of field. A good part of the key is out of focus. Deep DOF should show everything to infinity in focus.
An indication of Depth, maybe, but not very strong Depth of Field here. The bulb of the key is out of focus in the foreground, whilst the slot and key touching it are perfectly in focus.