Which sequence is an arithmetic sequence? 
选项为:A:$$1$$, $$2$$, $$4$$, $$5$$, $$7$$, $$8$$, $$10$$, $$11$$, $$\cdots$$  B:$$1$$, $$2$$, $$1$$, $$2$$, $$1$$, $$2$$, $$1$$, $$2$$, $$\cdots$$  C:$$2$$, $$5$$, $$8$$, $$11$$, $$14$$, $$17$$, $$21$$, $$\cdots$$  D:$$5$$, $$10$$, $$15$$, $$20$$, $$25$$, $$30$$, $$35$$, $$\cdots$$  请回答其中一个选项.