English

True narcolepsy is the sudden and irresistible onset of sleep during waking hours. True narcolepsy is extremely dangerous.

a.  While true narcolepsy is the sudden and irresistible onset of sleep during waking hours and is extremely dangerous.
b. The sudden and irresistible onset of sleep during waking hours, which is true narcolepsy but extremely dangerous.
c. True narcolepsy is the sudden and irresistible onset of sleep during waking hours, yet narcolepsy is extremely dangerous.
d. True narcolepsy is the sudden and irresistible onset of sleep during waking hours, and it is extremely dangerous.
  1. d. The conjunction and in this sentence indicates also. Choice a is wrong because it is a sentence fragment. Choice b makes no sense; choice c prepares the reader for a contrast but fails to deliver: narcolepsy is occurs in both main clauses.

Test ID: 461
Source: 501 Grammar and Writing Questions