Polyandry is the correct answer for the custom or practice of having more than one husband at the same time. Polyandry is a form of polygamy, which is the practice of having multiple spouses. In polyandry, a woman has multiple husbands concurrently.

Explanation:
Polyandry is a relatively rare form of marriage found in certain societies around the world. It is most commonly practiced in societies where resources are scarce, and it serves as a way to manage limited resources more efficiently. In these societies, brothers often marry the same woman, forming a fraternal polyandry system.

Key Points:
1. Definition: Polyandry is the custom or practice of having more than one husband at the same time.
2. Polygamy: Polyandry is a form of polygamy, which refers to having multiple spouses.
3. Rare Practice: Polyandry is less common compared to other forms of polygamy, such as polygyny (having multiple wives).
4. Resource Management: Polyandry is often practiced in societies with limited resources, where it serves as a way to share resources more effectively.
5. Fraternal Polyandry: In many polyandrous societies, brothers marry the same woman, forming a fraternal polyandry system.
6. Cultural Variations: Polyandry can vary in its cultural context and specific practices across different societies.
7. Examples: Polyandry has been observed in various regions, including parts of Tibet, Nepal, India, and Africa.
8. Social and Economic Factors: The practice of polyandry is influenced by social, economic, and cultural factors specific to each society.
9. Gender Dynamics: Polyandry challenges traditional gender norms and expectations regarding marriage and family structures.
10. Modern Perspectives: In contemporary times, polyandry is rare and often viewed as unconventional or taboo in many societies.

Overall, polyandry is a unique practice that allows for the sharing of resources and responsibilities among multiple husbands in certain societies. It highlights the diverse range of marriage arrangements found across different cultures and serves as a reminder of the complexity of human social relationships.