According to C. Wright Mills, sociologist study:

The correct answer is Option (1) → Links between personal troubles and social issues

Option (1) Links between personal troubles and social issues — Correct. C. Wright Mills wrote that sociology helps to map the links between ‘personal troubles’ and ‘social issues’. Personal troubles are the worries of one person, such as fear about one’s future job; social issues are the larger patterns of society, such as unemployment, that lie behind many such worries.

Option (2) Only modern industrial society — Incorrect. Sociology studies all kinds of societies, tribal, rural and urban, past and present, not only modern industrial ones.

Option (3) Problems of self-reflexivity — Incorrect. Self-reflexivity is the ability to look at oneself as others see one, which sociology helps to develop. It is not what Mills said sociologists study.

Option (4) Emotional life of the individual — Incorrect. The emotions of one person are mainly the field of psychology. Sociology looks at the individual only in relation to the wider society.