Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 26 to 30.

According to a recently published study, people who only get six or seven hours of sleep have longer life (26)_________ than those who sleep eight or more hours. “The idea that we need eight hours of sleep is completely unscientific,” said Professor Daniel Kripke, who led the study. The methods used, (27) _________, have been criticised. Investigators relied on people's own accounts of how long they slept, (28) _________ could be rather imprecise, as no one really knows when they fall asleep.
Contrary to Professor Kripke's findings, (29)_________ experts believe that getting insufficient sleep is a serious problem. What all scientists agree on is that more research is needed to discover exactly what the relationship is between sleep and longevity. This research is essential because with all the (30) _________ of modern life, such as cable TV and the Internet, it seems that a good night's rest is becoming increasingly rare.
(Adapted from Mastermind Use of English)