Hello aspirant,

You can do BSC after completing 3 years of polytechnic.

criteria for BSC is 10+2 from recognized board.

After completing 3 years of polytechnic you can do engineering or BSC it depends on you.But all university do not consider 10+3 years polytechnic criteria they need fixed 10+2 criteria from recognized board.

Still many universities are there which accept both criteria.

If you tell me for which state and for which university you are asking I will tell you in detail.

Hopes this helps