IMO C
According to the traffic engineers who scrutinized its new route, an escalating amount of stopped vehicles entered from the highway recently developed by city planners, which created more gridlock and also possibly disrupting other traffic patterns.
A. an escalating amount of stopped vehicles entered from the highway recently developed by city planners, which created more gridlock and also possibly disrupting
Here, WHICH refers to city planners. It's not the city planners that created gridlock.. It's the stopped vehicles.
Also, created more gridlock AND ....disrupting are not parallel.
WRONG.
B. an escalating amount of stopped vehicles entered from the highway recently developed by city planners, and it created more gridlock and also possibly disrupted
IT is used to refer to stopped vehicles which us plural.
Also, ENTERED, CREATED, and DISRUPTED are all parallel grammatically, but logically CREATED and DISRUPTED are sub clause because "the entered stopped vehicles results in both CREATE and DISRUPT event and thus we must preserve the authors intent.
WRONG.
C. an escalating amount of stopped vehicles entered from the highway recently developed by city planners, creating more gridlock and also possibly disrupting
Parallel structure is correct. ENTERED is main verb and (creating and disrupting) are correctly structured as parallel constructs which are not parallel to ENTERED unlike B. It clearly shows that create event and disrupt event ARE A RESULT OF entered stopped vehicles.
CORRECT.
D. the highway recently developed by city planners, recently entered by an escalating amount of stopped vehicles, created more gridlock and it possibly disrupted
Same issue as B. ENTERED, CREATED, DISRUPTED change the authors intent to show that create and disrupt events are the result of entered vehicles. Also, the use of recently twice is awkward.
WRONG.
E. the highway recently developed by city planners, recently entered by an escalating amount of stopped vehicles, creating more gridlock and it possibly disrupted
This option contains a series of modifiers and therefore the main verb is missing resulting in Fragment.
WRONG.
Final answer is C
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