Found some info. about the AOS status from

internet. It says"

"...
Adjustment of status is discretionary-- it is not guaranteed that the INS will approve the application. Therefore, the foreign national should keep in mind the possibility that he or she will have to go through consular processing (i.e., obtaining an immigrant visa at a U.S. consulate) if the adjustment application is denied.
..."

Does this mean that if I-485 is denied one can still apply an immigration visa outside US? If so what immigration visa do you apply? (which category? i-485 again?) Can anybody explain? Thanks!