Question #N1105

The researchers’ experiments showed that, in contrast to earlier studies, the brain regions most active during sleep are not always the same in all individuals, and that this variation is related to each individual’s unique sleep cycle. Which choice best combines the sentences at the underlined portion so that it conforms to the conventions of Standard English?

The researchers’ experiments showed that, in contrast to earlier studies, the brain regions most active during sleep are not always the same in all individuals, and that this variation is related to each individual’s unique sleep cycle.
A. the brain regions most active during sleep are not always the same in all individuals; this variation is related to each individual’s unique sleep cycle.
B. the brain regions most active during sleep are not always the same in all individuals, this variation is related to each individual’s unique sleep cycle.
C. the brain regions most active during sleep are not always the same in all individuals; and this variation is related to each individual’s unique sleep cycle.
D. the brain regions most active during sleep are not always the same in all individuals, and this variation is related to each individual’s unique sleep cycle.

Correct Answer is: B

Choice B is correct because it combines the two sentences with a comma and a coordinating conjunction, which is the correct way to combine two independent clauses. Choice A is incorrect because it uses a semicolon to join two independent clauses, but a semicolon can only be used to join two independent clauses when the second clause explains, illustrates, or expands on the first. Choice C is incorrect because it uses a semicolon to join two independent clauses, but a semicolon can only be used to join two independent clauses when the second clause explains, illustrates, or expands on the first. Choice D is incorrect because it uses a comma to join two independent clauses, but a comma cannot be used to join two independent clauses without a coordinating conjunction.