An electric vehicle differs mechanically from a combustion engine car. When the accelerator is pressed, energy flows from a battery to a motor ______ generating instant torque without the need for shifting gears.
Which choice completes the text so that it conforms to the conventions of Standard English?
thereby
thereby—
thereby,
thereby:
Correct Answer: C
Choice C is the best answer. The word "thereby" introduces a participial phrase ("generating instant torque") that modifies the action of the previous clause. Standard convention uses a comma to set off this modifier.
Choice A is incorrect because it lacks the comma needed to separate the independent clause from the modifying phrase. Choice B is incorrect because a dash creates an overly dramatic break that is not suited for this logical connection. Choice D is incorrect because a colon is used for lists or explanations, not to introduce a modifying participial phrase.