Allison and bob have chosen not to have any children because they feel their careers are more important. according to sociologists, they are known as

Child-free people

Explanation:

There are several reasons for sociologists to say that these kind of people and (even 7 brutal and ruthless reasons why women don't want to have children according to google search engine investigation)  diverse crucial researches on that behalf stating this conclusions:

That kind of people are

1 Selfish (but ironically)

2 Happier.

a is the final ! : )