$$151$$ traffic ambassadors lined up neatly in a straight line (at equal distances from each other) on a highway to promote traffic laws. After completing their task, at which position of the highway should they assemble in order to minimise their total walking distance from their respective positions to the assembly area? ． 
选项为:A:$$75^{}\text{th}$$ traffic ambassador\textquotesingle s position  B:$$76^{}\text{th}$$ traffic ambassador\textquotesingle s position  C:Between the $$75^{}\text{th}$$ and $$76^{}\text{th}$$ traffic ambassadors\textquotesingle~positions  D:Any position on the highway  请回答其中一个选项.