Need model number

Bought this phone used and though this is only an 8GB phone the back cover reads 16 GB so I assume that the model number printed there is also incorrect. I looked under settings/general/about and scrolled down to Model but it doesn't even come close to what is given on the link to help decide which version of ios to download. Those three choices all start off with the letter "A", the model given in the about section of this phone begins with "MC". I just upgraded to version 6.1.6. Any suggestions as to how to know which firmware to download?