It used to be the case, and it may still be the case, but things are changing in the Army ROTC world, so you may or may not be able to do this.
The first thing everyone considering the SMP program should know is that YOU CANNOT CONTRACT WITH ROTC UNTIL YOUR SOPHOMORE YEAR AT THE EARLIEST!!!
So, what does that mean??? If you let that recruiter sign you up and send you to basic and AIT then you are an enlisted soldier in the reserves, even if you are enrolled in ROTC. If for some reason you don't get a scholarship or contract or if ROTC doesn't work out for you then you are still obligated to the reserves. If your unit gets deployed you are going. Until you contract with ROTC they own you. Once you contract with ROTC things are a little different and the priority is becoming an Officer and earning your degree.
The other thing to keep in mind is because we are going to be entering an environment where contracts are going to be harder to come by, you may only be offered a Guard/Reserve contract at some point. If that is all you are offered and your goal is AD then you will be stuck with a take it or leave it scenario and will still have that obligation.
Your other option is to go to school and enroll in Army ROTC first...then go talk to a recruiter about joining the guard or reserves. You will be eligible for less guard/reserve benefits, but the path to becoming an officer and being able to compete for AD will be less bumpy.
And Bull is absolutely right...you should be talking to the ROO at NAU.