Explanation:

- Polyandry (Option 3): This is when a woman has multiple husbands.

- In some Himalayan regions, like Jaunsar-Bawar, this was practiced historically.

- The system ensured land wasn't divided among heirs, maintaining family wealth.

- Monogamy (Option 1): One person is married to one partner at a time.

- Most common form of marriage worldwide.

- Polygamy (Option 2): General term for having multiple spouses.

- Encompasses both polyandry and polygyny.

- Polygyny (Option 4): One man has multiple wives.

- Practiced in various cultures for different reasons, but not prevalent among the Khasa tribe.

- Correct Answer: Polyandry (Option 3)

- Practiced among the Khasa tribe historically.

- Managed land division and family dynamics effectively.