Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions from 45 to 46.
We spend about one-third of our lives sleeping. We know relatively little about sleep.
A. We know relatively little about sleep; as a result, we spend about one-third of our lives sleeping.
B. We spend about one-third of our lives sleeping so that we know relatively little about sleep.
C. Despite spending about one-third of our lives sleeping, we know relatively little about sleep.
D. We shall know more about sleep if we spend more than one-third of our lives sleeping.