I'm not really sure how your school works... and I think you should call the college and ask them.
Here's just my opinion on this: your rank shows your grade position in relation to all the people in your grades, not just the people taking your classes. That's why people here complains about how they're in the harder classes, which would drop their GPA and their class rank would drop too and it really sucks. Although people in US schools generally don't have a particular career path in high school, but students do take a bunch of different courses. The school still rank students in their grade together regardless of what individual subjects they have taken.