CBSE 12th

You really need some of your family members to convince them. If you are really that much intelligent, apply for a scholarship and then convince them. It is you only who actually understands the real thinking of your parents. Identify the level of their strictness over this issue.
Keep the pot boiling every now and then that you really want to do something in life and here in India, your life is hell. You can give examples of recent scams, murders, unemployment, and a crime against women.
Tell them by showing pics, videos, and news about the foreign countries like Canada, NZ and Australia that there is hardly any crime as compared to India.
Show them that the wage rate is really good. Show them that the studies, life, environment are world-class over there.
Tell them that you really want to achieve something in life before getting married.
Most of the parents here want their daughters to get married and then they don't care where ever she goes.
But what matters is before marriage.
You really need to fight your fight.
There might be times when there will be tensed atmosphere at your home over this issue. But just remember, everything can be done in life provided that you really fight for it.
If they pressurize to get married, tell them that you will never get married unless they send you abroad.
Also, get your mom on your side.
Tell her that she doesn't want to live in this cheap streets where snatchings, rapes, grave crimes occur every now and then.
In Australia, NZ and Canada, women go for outings, to malls, shopping at night alone but hardly anything like India happens. Because people are actually different.
They give importance to humans. Little happenings are everywhere but nothing to worry about.
Good luck.