In csab obc rank is considered or General rank in that Al is shown OBC-NCL Al means what
There after JOSAA will try to allot your highest priority course.
The process is it will check your highest priority course ranks .If you are able to get it in the general rank, then seat will be offered in general category. If you aren't getting under the general category but if you have a reservation then they will check whether u are getting it under reservation category. If you are getting the seat then you will be offered under reservation quota i.e. OBC/SC/ST rank.
Even if u aren't getting under reservation quota then they will proceed to the next priority i.e. your 2nd option.
Then this whole process continues until you get a seat.
But for damn sure they will try to give a seat of higher priority.
NOTE THAT HIGHER PRIORITY MEANS ACCORDING TO YOUR ORDER OF APPLYING OPTIONS, BUT NOT ACCORDING TO RANKING OF THE COLLEGE
I think all your doubts are clarified and hope u got a clean idea about allotment of seats.
If u still have doubts please feel free to write me.