Nobody knows exactly how many languages there are in the world, partly because of
the difficulty of distinguishing between a language and the sub-languages or dialects
within it, but those who have tried to count typically have found about five thousand.
A. and the sub-languages or dialects within it, but those who have tried to count typically
have found
B. and the sub-languages or dialects within them, with those who have tried counting
typically finding
C. and the sub-languages or dialects within it, but those who have tried counting it
typically find
D. or the sub-languages or dialects within them, but those who tried to count them
typically found
E. or the sub-languages or dialects within them, with those who have tried to count
typically finding

OA A

Is usage of within it correct???