Many of the examples in the new book about the Kamuxa culture were taken—and indeed discussed extensively in—sources that
had been compiled at an earlier time by field researchers in the nineteenth century but were not available until very recently. Meaning Analysis:
This sentence talks about two characteristics of many of the examples in the new book about the Kamuxa culture. Many of these examples were:
a. taken FROM sources that…
b. discussed extensively IN sources that…Error Analysis:
The verb “taken” must be followed by preposition “from”. If we remove the part written between the dashes, then the sentence will read …examples… were taken… sources… This is ungrammatical.PoE:
A. taken—and indeed discussed extensively in—sources that: Incorrect
for the reason stated above.
B. taken from sources—and indeed discussed extensively—that: Incorrect.
The information between the dashes fails to connect with the rest of the sentence.
C. taken from—and indeed discussed extensively in—sources that: Correct.
Intended parallelism is maintained.
D. taken from—and indeed discussed extensively—in sources that: Incorrect.
If we strike out the information between the dashes, the sentence will read “… examples… were taken FROM IN sources…”. Use of two prepositions together is ungrammatical.
E. taken—and indeed discussed extensively—from sources that: Incorrect.
“discussed extensively” must be followed by preposition “in” to connect logically with rest of the sentence.
Hope this helps.