A couple things:
argv isn't available globally, so you're probably not able to compile your program because you're using it in this method. You should use the
candidates array instead, since that is available globally, and it's set for you in main.
preferences[voter + i][i] this line isn't doing anything. You should be setting an element in this array to a value. Also, re-read how that array should be structured. Because of how the testing works, you have to set that array exactly how it's described in the problem, and it doesn't look like you have that right.
Also, you're not using the
rank variable that's passed into the method. CS50x passed it in, so you should be using it. (Fixing the previous problem will mean you have to use it.)