Which One of These Is the Best Example of a Co-Parenting

Which one of these is the best example of a co-parenting arrangement?

A) Tyler and Samantha are divorced, and Tyler has custody of their two children while Samantha is in prison.
B) Dan and Sara are single parents and good friends who often have dinner together with their respective children.
C) Marisa and Gwen are married and together are raising Gwen's children from her first marriage.
D) Although Natasha receives child support from her ex-husband, he has not seen their three children in four years.