I thought her nice and honest _______ I met her.A.first time B.for the first time C.the first time D.by the first time 应该选择什么,请列出相关语法,

1 the first time (是连接词，用于主将从现和主过从过的句子中)，
I was a boy of 16 THE FIRST TIME(=when) I came to this place (主过从过)
==I was a boy of 16 WHEN I came to this place FOR THE FIRST TIME.
You will like him THE FIRST TIME(==when) you see him next week(主将从现)
==You will like him WHEN you see him FOR THE FIRST TIME next week.
2 for the first time （第一次，往往用于简单句）
In 2009,he came to Shanghai for the first time
3 by the first time (翻译：在第一次以前)
Those people had heard so much about him BY THE FIRST TIME they saw him himself last year. (那些人在去年见到他本人以前就已经听说过他的许多事情)
for the first time 相当于一个状语，所以它可以随便放哪儿都行，first time,第一次，作为一个名词组，the first time ,可以作为先行词引导时间状语从句，也可和first time一样，by the first time,也是作为一个状语词组，到第一次为止

选C吧，语感告诉我的。

选C
这个用法叫做时间状语作连词
the ＋序数词＋time，还有表示瞬间的，比如immediately都可以作连词来引导句子

C:序数词+年，月，时等表示时间状语

Cthe first time 第一次,是名词,在句子中只能做名词的成分.at the first time 是介词短语,是“在第一次” for the first time 也是第一次,是个副词短语,在句子中做状语.例子：I felt nervous the first time I gave ...

选c.
the first time 在这里相当于连词用，意为“第一次……就……”，固定用法，另外加介词或者不加定冠词都是错误的。
相同用法短语还有the moment，the second，the instant等