Final answer:
While the provided data does not specify which cohabiting union type is most likely to marry, it can be inferred that cohabiting unions with children might be more likely to marry due to the benefits and stability it provides for raising children.
Step-by-step explanation:
The question about what cohabiting union is most likely to marry touches on the patterns of relationship dynamics leading up to marriage.
Cohabiting couples often live together to spend more time together or to save money, and many view cohabitation as a 'trial run' for marriage.
According to the data provided, it is not outrightly stated which type of cohabiting union is most likely to marry, but based on U.S. Census Bureau statistics, the vast majority of cohabitating relationships eventually result in marriage.
Furthermore, children, social acceptance, financial stability, and the decreasing stigma around cohabitation play significant roles in whether cohabiting couples will transition to marriage.
Since it appears that cohabiting unions with children may provide a more stable environment for raising offspring and because societal norms tend to favor married parents for the benefits toward children, it is possible that cohabiting unions with children would have a higher propensity to transition into marriage.
This would align with the statistic that parental marital status is a significant indicator of a child's life advancement and that children benefit from the marriage of their parents.