Which power cable is correct for my WD portable hard drive?

I have a WD portable drive for what was my Macbook Pro. However, the Macbook died, we moved house and I cannot find which power lead I need to power it up. As these things are quite delicate and very sensitive to the wrong amperage being applied, I want to ensure I get it right.

I now have an 27" Mac and want to check the contents of the drive. Can anyone help?

Apart from the serial number, it has:
R/N :D3C

Who can help?

That model number corresponds to a 2TB WD Elements Desktop. The following link contains information related to the unit’s power adapter.