Complicated issue regarding D2 visa

HELLO every one !!!

I need some information regrading my visa. I am a graduate student, I enroled in combined course (Master +PhD), officially it take 4 years to complete, so the dureation in my ARC is 4 years. But in the meanwhile after 2 years I complete Master and change my degree from combined course to Master coures only. and will graduate this Feb. But still in my ARC there are 2 years to expire. So, I want to ask that with my graduation my visa will expire or I can stay 2 years on this visa (student visa).