Mac Forums

i just purchased a macbook pro and i'm very unfamiliar with apple. i would like to download adobe reader for it, but then i was asked to select an operating system and the choices i was given for macs were.... "Mac OS Intel 10.5.6 - 10.6.0" "mac os intel 10.4.11- 10.5.5" "mac os powerpc 10.5.6- 10.6.0" or "mac os powerpc 10.4.11- 10.5.5". i'm not sure what mine would be. thank you