Sentence Correction

Gmatprep SC

In Hungary, as in much of Eastern Europe, an overwhelming proportion of women work, many of which are in middle management and light industry.
A. as in much of Eastern Europe, an overwhelming proportion of women work, many of which are in
B. as with much of Eastern Europe, an overwhelming proportion of women works, many in
C. as in much of Eastern Europe, an overwhelming proportion of women work, many of them in.
D. like much of Eastern Europe, an overwhelming proportion of women works, and many are.
E. like much of Eastern Europe, an overwhelming proportion of women work, many are in.

OA - C ; I chose A because I had learned from OG 12 Q 43 (similar construction) that many of them
is incorrect

OG 12 Q 43

Laos has a land area about the same as Great Britain but only 4 million in population, where many are members of hill tribes ensconced in the virtually inaccessible mountain valleys of the north.

A. about the same as Great Britain but only 4 million in population, where many
B. of about the same size as Great Britain is, but in Laos there is a population of only 4 million, and many
C. that is about the same size as Great Britain's land area, but in Laos with a population of only 4 million people, many of them
D. comparable to the size of Great Britain, but only 4 million in population, and many
E. comparable to that of Great Britain but a population of only 4 million people, many of whom

OA - E .

This is what OG says about C

The reference of them is unclear and the expression is generally awkward.

I know there are other reasons for C(OG 12 Q 43) to be wrong but ,since OG mentions them as incorrect , so I made a note that such a construction is wrong and thus discarded option C (Gmatprep SC)

I think I am mixing the two constructions , can some clarify ?