Quote:
Until Berta and Ernst Scharrer established the concept of neurosecretion in 1928, scientists believed that either cells secreted hormones, which made them endocrine cells and thus part of the endocrine system or conducted electrical impulses, in which case they were nerve cells and thus part of the nervous system.
a) either cells secreted hormones, which made them
b) either cells secreted hormones, making them
c) either cells secreted hormones and were
d) cells either secreted hormones, in which case they were
e) cells either secreted hormones, which made them
There are two issues here. 1. The parallelism of correlative conjunctions 'either … or' and 2. The parallelism of the relative clause after the word 'hormones'
AS per the first tenet, only D maintains the proper parallelism and hence is the correct choice. In the case of the second tenet, yet again D is the only choice that uses the 'in which' format parallelly for both the items.
However, there may be no reason to look for all the errors in a given choice in the hall, if one can be damn sure about the correlative conjunction parallelism alone in this case.
However, if parallelism were not an issue, then the reference of 'which' and the modification of 'making' would be major issues and the easiest way of dumping three choices to the good.
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Thank you Daagh for your time on GMAT Club and all your contributions! Thank you for everything you did!Your work will remain a great tribute to you here on GMAT Club!
-bb