Which of the following is NOT a definition of family?

Which of the following is NOT a definition of family?
 
  a. Family is the primary group in which members share close and personal relationships, which are developed through shared activities, that last over a prolonged period of time.
  b. A family group often exerts tremendous influence over its members in terms of behaviors, beliefs, communication styles, cultural transmission, social skills and efforts to meet basic human needs.
  c. A family is a group of replaceable members who are incorporated through birth, adoption, commitment or marriage.
  d. A family group helps members learn unique ways, with different capabilities and different levels of success in meeting their members' needs.