Simple quick Question about ePSXe emulator the playstation 1 emulator.

Well when I download a game like tenchu 2 for example. I got 2 Files that can be opened by the emulator. What i wanna know is which one do i choose to open with the emulator, I tried both and they seem to open with both but wanna know which one for sure is the correct file to always open with to not have a problem. The 2 files I have to choose from if you haven't guessed already are .img and .ccd
Thank you for taking time to answer.

You shouldn't worry, if you can open and play both you should be good, clicking on the wrong one will just point to the next one, since they are linked...But to be honest I have no clue which is the main file XD

you open the .cue file