OFFICIAL EXPLANATION
Urban gentrification, an informal cause for the economic eviction of lower-income residents, a process in which more affluent people acquire housing property cheaply in poor neighborhoods and the entry of upscale businesses and commerce combine driving up real-estate prices, rents, and property taxes.A. a process in which more affluent people acquire housing property cheaply in poor neighborhoods and the entry of upscale businesses and commerce combine driving
Incorrect.
This answer choice is grammatically incorrect -- it is a fragment.
This sentence is a fragment because the main subject Urban gentrification lacks a conjugated verb that matches it (remember that verbs in modifying and relative clauses do not count here):
Urban gentrification [, an informal cause for the economic eviction of lower-income residents,] a process in which [X].
In addition, the construction combine driving is grammatically incorrect: the modifier driving should be separated from the preceding part of the sentence by a comma.B. a process in which more affluent people acquiring housing cheaply in poor neighborhoods and the entry of upscale businesses and commerce combine and which drive
Incorrect.
This answer choice repeats the original mistake -- it is a fragment.
In addition, the use of the second relative pronoun and which, creates a parallelism: a process in which ... and which. However, this parallelism introduces a mistake - the singular subject process does not agree with the plural verb drive.C. is a process where more affluent people acquire cheap housing properties in poor neighborhoods and, combined with upscale businesses and commerce entering, is driving
Incorrect.
While this answer choice corrects the fragment mistake in the original sentence, it either changes the meaning of the original sentence or is grammatically incorrect, depending on how you read it. To understand this double-edged mistake, break down the sentence as follows:
Main clause: Urban gentrification, ..., is a process where :
Relative clause: more affluent people acquire cheap housing properties in poor neighborhoods
Final part?: and, combined with ..., is driving up real-estate prices, rents, and property taxes.
If the final part of the sentence belongs to relative clause, it creates a Subject-Verb Agreement mistake: the singular verb is driving does not agree with the plural subject people.
If, however, the final part belongs to the main clause, it changes the meaning of the sentence. In the original sentence it was affluent people's acquisitions that combined with upscale business entering; however, here it is the process of urban gentrification that combines with upscale business entering.
Urban gentrification, ..., is a process where [..] and, combined with upscale businesses and commerce entering, is driving up [...].
D. a process where the combination of more affluent people acquiring cheap housing properties in poor neighborhoods and upscale businesses and commerce entering drives
Incorrect.
This answer choice repeats the original mistake -- it is a fragment.
This sentence is a fragment because the main subject Urban gentrification lacks a conjugated verb that matches it (remember that verbs in modifying and relative clauses do not count here):
Urban gentrification [, an informal cause for the economic eviction of lower-income residents,] a process in which [X].
In addition, Verb+ing (entering) can be used as a noun replacement only when there's no actual noun. Since there is a real noun -entry- it should be used.E. is a process in which more affluent people acquiring cheap housing properties in poor neighborhoods and the entry of upscale businesses and commerce combine to drive
This answer choice corrects the fragment mistake in the original question by by adding the verb is in the main clause (Urban gentrification....is a process...).
It also corrects the grammatical construction by changing the faulty construction combine driving to combine to drive. This construction (with conjugated verb + to V) expresses the fact that drive is the result of combine.