Answer:
b. Sociologists try to keep the definition open to encompass all types of people who are emotionally close to each other.
Explanation :
In the field of sociology, the sociologists tries to define family as a group of people who come close to each other and they find comfort in their presence. These people are called as a family who are emotionally attached to one another.
Family tends to spend time with each other. They understand and cooperate with each other at times of need. They are socially bonded to one another.
Members of the family are emotionally close to each other.
Thus the anwser is --
b. Sociologists try to keep the definition open to encompass all types of people who are emotionally close to each other.