[Grammar] 【each】 vs. 【either】

[dodonaomik]

______ party shall notify the other party of the ratification by their respective authorities.

A Either
B Each

question: I feel 【each】> or = 3 aspects, 【either】=2 aspects, so I think 【either】 is right and 【each】 is wrong! But why is the key opposite?
Thanks!

[2006]

Originally Posted by dodonaomik

______ party shall notify the other party of the ratification by their respective authorities.

A Either
B Each

question: I feel 【each】> or = 3 aspects, 【either】=2 aspects, so I think 【either】 is right and 【each】 is wrong! But why is the key opposite?
Thanks!

"each" can be used for only two of something, and only "each" is correct here.
Here 'Each party shall...' means 'Both parties shall...'. The intended meaning is that both parties must notify the other party.

'Either party' and "shall" are not compatible together.
A sentence like 'Either party may cancel the agreement, thereby making it null and void.' would be correct.