Uh all of them are pretty much right. I would say C that one seems to have an all around summary
Answer: 1: whom 2: who 3: who
Explanation: This is what I think. Apoligies if I got any wrong, I don't use the word 'whom' very much.
- <em>the answer "a" Is correct !</em>
<em>In his pre presidential years he was one of America's greatest diplomats—formulating, among other things, what came to be called the Monroe Doctrine—and in his post presidential years (as a U.S. congressman, 1831–48) he fought against the expansion of slavery.</em>