According to Crawford, becoming a mother is a major life transition because it

A) is a kind of biological destiny for women.
B) involves changes in work, lifestyle, and relationships with significant others.
C) is pathological not to feel positive about motherhood.
D) involves changes in the physical self but not the psychological identity of women.

Crawford argues that becoming a mother involves significant changes in multiple domains of a woman's life, including work, lifestyle, and relationships. It is not just a biological destiny, and it is not necessarily pathological if a woman does not feel entirely positive about motherhood. Becoming a mother can also involve changes in a woman's psychological identity, not just her physical self. Therefore, option (B) best represents Crawford's perspective on the major life transition of becoming a mother.