Sanda is a Burmese emerging adult who recently got married and is now considered an adult in her culture. Why does marriage constitute the attainment of adulthood in Sanda's culture?

Marriage constitute the attainment of adulthood in Sanda's culture because in many culture, like the Burmese one, marriage is the rite of passage that constitute the beginning of the adult life. Rite of passage are common in pretty much all culture and they are an institutionalize form of proving or demostrating tothe member of a culture that a certain quality or moment has arrived.