Which of the following represents the shared identity in Roman marriage?

The phrase "Quando tu Gaius ego Gaia" symbolizes the shared identity in Roman marriage, as it exemplifies the traditional agreement made between the couple upon their union. This expression signifies that when one partner, usually the man, identifies himself, the other partner, typically the woman, complements that identity through her own. This linguistic formality reflects the social and legal bond that is created in marriage, where both individuals are seen as unified in their roles within that relationship.

The concept encapsulated in this phrase allows for a cultural understanding of marriage in Roman society, emphasizing both partnership and individual identity within the institution. In Roman beliefs, the roles of husband and wife were interlinked, and this phrase acts as a verbal acknowledgment of that connection.