If I do an import with just a single question in the file (shown below and attached) that uses an apostrophe at column 50, the import fails with the error message: "Cannot insert question".
aaaaaaaaaa xxxxxxxxxxxxxxxxxxxxxxxxxxxx yyyyyyyyy's
A. test1
B. test2
ANSWER: A
However, if I move the apostrophe to column 49, it imports just fine.
This is not a UTF-8 issue as I've verified that's the file's encoding. I don't know what version of Moodle I'm using, but I assume it's relatively recent since my university uses it quite extensively.
My guess is this is a bug related to Moodle using the first 50 characters of the question as the title of the question when importing. Some programmers need to be severly flogged for this.