求助一道prep上的语法题

放下那个鸡腿

The contractor and the engineer agree on the cause of the bridge failure, but both blame the other.
A.both blame the other
B.each blames the other
C.each blame the other person
D.both are blaming the other
E.each blames one another


请问为什么E选项的one another不能，而要用the other？不是才两个人而已吗？
求回答！过几天就要考试希望能搞懂︿(￣︶￣)︿

Bradz

one another is usually used when there are more than 2 parties. i think.
2 parties: they love each other - A loves B, B loves A

more than 2 parties: they love one another - A loves B and C, B loves A and C, C loves A and B.