First: the question at the top has been transcribed incorrectly. Follow this link (thanks uymba!) to read the correctly transcribed question: https://www.beatthegmat.com/retirement-t ... 25376.html

Second: please DO NOT post questions for which you cannot look at the original source AS YOU ARE TYPING IN THE QUESTION. Sorry to go "all caps" on you, but this is critically important. Everyone is now trying to figure out which one is the correct choice, and re-writing their notes and driving themselves crazy... and it turns out that the correct choice isn't even there. Obviously, that's not an effective way to study!

Third: karmayogi, nice summary of when to use "so." Think of "so" as similar to a pronoun, except that instead of replacing a noun, it will replace either a verb or an entire clause (verb + other words). Here's the (correctly transcribed) original sentence:

A study on couples' retirement transitions found that women who took new jobs after retiring from their primary careers reported high marital satisfaction, more so than those who retired completely.

The "so" refers to "reported high marital satisfaction" (a verb, some adjectives, and a noun).

Each group reported a different level of marital satisfaction; the "so" allows us to refer to that concept without repeating all of those words.

you're welcome! (But don't attach a file with the sentence - for technical reasons, it's a lot harder to answer questions that way. Do type it out, but do it while looking at the original source and double-check your transcript before you post it!)

are you sure that the correct version of (c) isn't actually "more so than those who retired..."?

if so, that would be a valid comparison: you'd be comparing the WOMEN who took new jobs to the WOMEN who retired completely.

choices (a), (b), and (e) all have an absurd meaning: they imply that the study somehow compared the satisfaction of the women who had taken new jobs to the satisfaction that would be experienced by the same women if they had retired completely.
studies clearly can't measure hypotheticals such as this, so we need to replace this meaning by one that actually makes sense. if the study reports the satisfaction of one group of women in comparison to that of another group of women, then it actually makes sense.
if we add the extra "those" to choice (c), this is exactly its meaning, so it passes the clarity test as well.

ok, i just saw stacey's response.

for real, people: TRANSCRIBE QUESTIONS DIRECTLY.
if they are not from a source that can be literally cut and pasted, then transcribe them verbatim, as you are looking at them.

Here's the relevant text of the correct answer:

"women who took new jobs after retiring from their primary careers reported high marital satisfaction, more so than those who retired completely"

category A: women who retired and then took new jobs
category B: women who retired and did NOT take new jobs

from the answer: category A women reported high marital satisfaction, more marital satisfaction than category B women

"normal language" translation: category A women reported higher marital satisfaction than did category B women