请教一个关于only的问题

今天看到一道题，两个选项只一the之差，却让我越想越糊涂

请教各位，one of  only eight Revolutionary War battles和one of  the only eight Revolutionary War battles 分别是什么意思？only 前面有the和没有the 区别在哪儿？

以后请把题目贴全，谢谢。

the定冠词的相比于没有定冠词的更具限定性，我想后面那种在war battles后应该还有些类似定从或其他的什么成分吧。

不好意思，这是网络课堂一道例题，因为我当时就是这一点想不清楚，是根据其他错误判断出正确选项的，所以当时觉得不需贴出整道题

以前的习惯用法都是one of the only+数词+名词复数，所以看到正确选项A，觉得不太对，再加上老师的讲解让我愈加糊涂。请各位赐教。这两种表达究竟区别在哪儿？各自含义是什么？

In June of 1989, Princeton Township approved a developer's plans to build 300 houses on a large portion of the 210-acre site of the Battle of Princeton, one of only eight Revolutionary War battlefields that had remained undeveloped.
(A) one of only eight Revolutionary War battlefields that had remained undeveloped
(B) one of eight of the only Revolutionary War battlefields that have remained undeveloped
(C) one of the only eight undeveloped Revolutionary War battlefields that remains
(D) only one of eight Revolutionary War battlefields to remain undeveloped
(E) only one of the eight remaining undeveloped Revolutionary War battlefields

忘画线了，不好意思

In June of 1989, Princeton Township approved a developer's plans to build 300 houses on a large portion of the 210-acre site of the Battle of Princeton, one of only eight Revolutionary War battlefields that had remained undeveloped.
(A) one of only eight Revolutionary War battlefields that had remained undeveloped
(B) one of eight of the only Revolutionary War battlefields that have remained undeveloped
(C) one of the only eight undeveloped Revolutionary War battlefields that remains
(D) only one of eight Revolutionary War battlefields to remain undeveloped
(E) only one of the eight remaining undeveloped Revolutionary War battlefields