Important variables in the family life cycle are age, marital status, and
a. presence of children.
b. primary motivation for purchases.
c. income.
d. level of involvement.
e. gender.

option A

Explanation:

the correct answer is option A  

an important variable in the family life is age, marital status, and Presence of Children.

As in a family, the presence of children is variable because as time passes the age of children keeps on increasing which reduces the number of children in the family.

hence, we can say that the Presence of Children is a variable in family life.

c it has to be i googled it

answer; can each be concretely realized in different ways;