A health study seeks to assess the relationship between hours of sleep per night and frequency of illness among adults. 100 adults are selected at random from the population of a large city. The table details the information for the 60 adults who sleep at least 7 hours each night.
| Hours slept/night | Illnesses in past 6 months | Illnesses in past 6 months | Total |
|---|---|---|---|
| 0 or 1 | 2 or more | ||
| 7 to 8 hours | 20 | 6 | 26 |
| More than 8 hours | 30 | 4 | 34 |
| Total | 50 | 10 | 60 |
To which of the following populations can the results of the study be generalized?
The 60 adults who sleep at least 7 hours per night
All adults in the large city
The 100 adults in the sample
All adults who had 2 or more illnesses in the past 6 months
