Final answer:
Susan's marriage to two different men at the same time is known as polyandry, which is a specific form of polygamy and is less common than polygyny.
Step-by-step explanation:
Susan lives in a society that approves her marriage to two different men at the same time. This type of marriage is called polyandry. Polyandry is a form of polygamy in which one woman is married to more than one man at the same time. While polygamy refers to a marriage involving multiple spouses and is more commonly encountered in the form of polygyny (one man married to multiple women), polyandry is less common and accounts for about 1 percent of the world's cultures. It is observed in some societies to address issues such as population growth, scarcity of resources, or to maintain property within a family.