Question #N1076

The main purpose of the study was to examine the effects of a new drug on the body’s immune system. Researchers recruited volunteers for the study, who were randomly assigned to either a treatment group or a control group. The volunteers in the treatment group received the new drug, while the volunteers in the control group received a placebo. The researchers then monitored the volunteers for a period of six months, measuring various immune system parameters. At the end of the study, the researchers found that the volunteers in the treatment group had a significantly lower incidence of infection than the volunteers in the control group.

Which choice best combines the sentences at the underlined portion to create a grammatically correct and stylistically effective sentence?
A. The volunteers in the treatment group received the new drug, while the volunteers in the control group received a placebo, and then they monitored the volunteers for a period of six months, measuring various immune system parameters.
B. The volunteers in the treatment group received the new drug, while the volunteers in the control group received a placebo; the researchers then monitored the volunteers for a period of six months, measuring various immune system parameters.
C. The volunteers in the treatment group received the new drug, while the volunteers in the control group received a placebo, the researchers then monitored the volunteers for a period of six months, measuring various immune system parameters.
D. The volunteers in the treatment group received the new drug, while the volunteers in the control group received a placebo; the researchers then monitored the volunteers for a period of six months, measuring various immune system parameters.

Correct Answer is: C

Choice C is the best answer. The sentence is grammatically correct and stylistically effective. The comma separates the two independent clauses, and the phrase “the researchers then” clearly connects the second clause to the first. Choice A is incorrect because the conjunction “and” is redundant and creates a comma splice. Choice B is incorrect because the semicolon creates a comma splice. Choice D is incorrect because the semicolon is redundant and creates a comma splice.