Question #N1174

The study found that in the early phases of the universe, the rate of expansion was much higher than it is now. It is known as the inflationary period. During that period, the universe expanded to the size that it is today, in a very short time. This period is followed by a slower rate of expansion, which is still occurring today.

Which choice best combines the sentences at the underlined portion to create a grammatically correct and clear sentence?
A. It is known as the inflationary period; during that period, the universe expanded to the size that it is today, in a very short time.
B. It is known as the inflationary period, during which the universe expanded to the size that it is today, in a very short time.
C. It is known as the inflationary period: during that period, the universe expanded to the size that it is today, in a very short time.
D. It is known as the inflationary period, and during that period, the universe expanded to the size that it is today, in a very short time.

Correct Answer is: B

Choice B is the best option because it correctly uses a relative clause to combine the two sentences. A relative clause is a dependent clause that describes a noun in the main clause. The relative clause "during which the universe expanded to the size that it is today, in a very short time" describes the noun "inflationary period." This makes the sentence grammatically correct and clear.