O、S、As 三种元素比较，正确的是                                  

A．电负性O > S > As，原子半径O < S < As

B．电负性O < S < As，原子半径O < S < As

C．电负性O < S < As，原子半径O > S > As

D．电负性O > S > As，原子半径O > S > As