On the premise that "If Xiaoqiang and Li Chao are not outstanding Communist Youth League members, then Zhou Hong is an excellent Communist Youth League member", if it is necessary to introduce "Li Chao is an outstanding Communist Youth League member",. Which of the following needs to be added as a prerequisite? ['Zhou Hong is not an excellent Communist Youth League member.', 'Sun Qiang is an excellent Communist Youth League member.', 'Zhou Hong is an excellent Communist Youth League member, while Sun Qiang is not an excellent Communist Youth League member.', 'Sun Qiang and Zhou Hong are not outstanding Communist Youth League members.']