The correct answer is (a) Khasis.
Diwali is a festival of lights that is celebrated by Hindus, Sikhs, and Jains. It is a time to celebrate the victory of good over evil, light over darkness, and knowledge over ignorance. It is also a time to give thanks for the blessings of the past year and to pray for good fortune in the coming year.
The Khasis are an ethnic group that lives in the northeastern Indian state of Meghalaya. They are a matrilineal society, which means that property and inheritance are passed down through the female line. The Khasis are also known for their unique culture and traditions, including their practice of polyandry.
Diwali is not a festival of mourning among the Khasis. In fact, it is one of the most important festivals of the year. The Khasis celebrate Diwali by lighting lamps, exchanging gifts, and feasting. They also visit the graves of their ancestors and pay their respects.
The other options are incorrect because they are not ethnic groups that celebrate Diwali. The Mundas are an ethnic group that lives in the eastern Indian state of Jharkhand. The Bhils are an ethnic group that lives in the western Indian states of Rajasthan, Gujarat, and Madhya Pradesh. The Tharus are an ethnic group that lives in the northern Indian state of Uttar Pradesh.