The economic processes of urbanization that have left many rural areas of the world underpopulated, while creating large concentrations of population in expanding cities, have had concomitant social effects such as causing family authority structures to weaken and to transform religious practices.

A. have had concomitant social effects such as causing family authority structures to weaken and to transform religious practices
B. have had concomitant social effects such as the weakening of family authority structures and transforming religious practice
C. has had concomitant social effects such as weak family authority structures and transformed religious practices
D. had concomitant social effects that caused family authority structures to become weaker and religious practices to transform
E. have had concomitant social effects such as the weakening of family authority structures and the transformation of religious practices

A - Incorrect.

This answer choice is grammatically incorrect. The construction A and B (causing and to transform) requires that A and B belong to the same part of speech. In this case, A (causing) is a non-conjugated verb of the V+ing form , whereas B (to transform) is a non-conjugated verb of the to V form.

Note that to weaken is not logically parallel to to transform, as drawing such a parallelism implies that family authority structures transform religious practices - a structure cannot logically transform a practice.

In addition, this answer choice is stylistically flawed. The word causing is redundant because it repeats the meaning contained in the word effects.

B - Incorrect.

This answer choice is grammatically incorrect. The construction A and B (the weakening and transforming) requires that A and B belong to the same part of speech. In this case, A (the weakening) is in the form if article+Ving, whereas B (transforming) is missing the article.

C - Incorrect.

While this answer choice corrects the Parallelism mistake in the original question, by creating a parallelism of two nouns (structures//transformation) it is grammatically incorrect. The singular verb has does not agree with the plural subject processes of urbanization.

What helps us identify this question as a Subject-Verb Agreement question as well as identify the mistake is the following stop signs:

Stop Sign: an X of Y subject (processes of urbanization is a plural subject)

Stop Sign: A long, complex subject or a great distance between subject and verb

In addition, causing family authority structures to weaken does not mean the same as weak family authority structures. The original sentence says only that authority structures became weaker (they might still be quite strong, but not as strong as before), while the corrected sentence states decisively that authority structures are weak.

D - Incorrect.

While this answer choice corrects the Parallelism mistake in the original question by creating a parallelism of two object phrases (authority structures to become weaker and religious practices to transform) it is grammatically incorrect, stylistically flawed and illogical.

The corrected sentence unnecessarily changes the Present Perfect tense in the original sentence to the Past Simple. The original sentence's use of the Present Perfect is correct, as the sentence describes actions that began in the past and are still relevant in the present. The use of the Past Simple is typically indicated by a specific time designation, but this sentence does not describe an action occurring at a specific time.

In addition, the word caused is unnecessary and redundant because it repeats the meaning of the word effects. This makes the corrected sentence illogical: the social effects aren't the cause of family authority structures becoming weaker; rather, the social effects (=outcomes, impacts, results) are the fact that family authority structures have become weaker.

E - Well done!

This answer choice corrects the Parallelism mistake in the original question by eliminating the redundant word causing and creating a parallelism of two nouns (the weakening and the transformation).