I believe the correct answer is A: Infants require a lot of care, leaving little time for the couple to be alone.
This particular moment in a family is called the Stage of procreation: it begins with expectant fatherhood, when the focus is on the next birth. The focus of the couple moves to the baby when it is born. The couple must balance conjugal life, raising children and wage-earning roles. It is necessary to administer the time in the corresponding proportion for all the activities, sometimes the bad administration produces internal problems in the relationship of the couple.