Final answer:
Children's adjustment to a parent's remarriage is improved by supportive relations between the noncustodial parent and the stepparent, which help reduce stress and provide stability during family changes.
Step-by-step explanation:
The factor that improves children's adjustment to a parent's remarriage is supportive relations between the noncustodial parent and the stepparent. Strong parent-child relationships are critical in helping children adapt to changes in family dynamics. This support helps to mitigate the stress and conflict that may arise from the formation of a stepfamily, which is often associated with interpersonal conflicts and can impede a child's sense of security and well-being. Moreover, a collaborative effort between the noncustodial parent and stepparent creates a more harmonious home environment, which can provide the child with stability and reassurance during times of change.