Researchers Reported That for Men,being Unmarried Increases the Risk of Depression.These

Multiple Choice

Researchers reported that for men,being unmarried increases the risk of depression.These findings were based on the medical records of 400 married men and 500 unmarried men.Since there is no random assignment,this conclusion is not justified because there may be lurking variables.Which of the following are possible lurking variables?
I: Rate of depression
II: Income
III: Type of employment
IV: Age
V: Gender

A) II,III,IV
B) III,IV
C) II,IV
D) II,III,IV,V
E) I,II,III