The ones digits of exponents based on $3$ follow the rule: $3, 9, 7, 1, 3, 9, 7, 1\cdots $  $50\div4=12R2$, which means the ones digit is $9$. 
What is the ones digit of the result of $3^{50}$? 
Options:
1. $$1$$ 
2. $$3$$ 
3. $$5$$ 
4. $$7$$ 
5. $$9$$ 