$$1+(5-1)\times 99=397$$. 
What is the $$100\rm th$$ number in the arithmetic sequence $$1$$, $$5$$, $$9$$, $$13$$, $$17$$, $$21$$, $$25$$, $$\cdots$$． 
Options:
[a] $$397$$ 
[b] $$399$$ 
[c] $$401$$ 
[d] $$403$$ 
[e] $$405$$ 