CAT Application Query for NEP 4-Year B.Com.

I'm currently pursuing a 4-year B.Com. (Honours/Research) under NEP, but my university allows us to exit after the 3rd year with a bachelor's degree.
I'm appearing for CAT this year, and if I get a good college, I'll exit after the 3rd year. Otherwise, I'll continue with the 4th year.
So while filling the CAT form, should I mention my course duration as 3 years or 4 years? Also, will choosing 4 years now cause any issue if I later exit after the 3rd year, or vice versa?