Researchers Have Found That People Who Report Having Trouble Sleeping

Multiple Choice

Researchers have found that people who report having trouble sleeping are more likely than others to become depressed. Which of the following conclusions, if any, follows from these data?

A) Sleeplessness increases the probability of becoming depressed.
B) People who are starting to become depressed have trouble sleeping.
C) Certain genes increase depression and also, independently, lead to sleep troubles.
D) None of these conclusions follow from the data.