$$1+1= 2$$, $$1+2 = 3$$, $$\cdots$$, $$5+8 = 13$$, $$8+13 = 21$$. 
The next number in the sequence $$1$$, $$1$$, $$2$$, $$3$$, $$5$$, $$8$$, $$13$$, $$\cdots$$ is． 
- $$21$$ 
- $$20$$ 
- $$19$$ 
- $$15$$ 
- None of the above 