The correct answer is C. Vajjika.
Maithili, Magahi, and Bhojpuri are all Indo-Aryan languages, which means they are part of the Aryan family of languages. Vajjika, on the other hand, is a Dravidian language.
Indo-Aryan languages are spoken by about 2.5 billion people in the Indian subcontinent and around the world. They are descended from Sanskrit, the ancient language of India. Indo-Aryan languages are divided into two main branches: Eastern Indo-Aryan and Western Indo-Aryan. Eastern Indo-Aryan languages are spoken in eastern and northeastern India, Bangladesh, and Nepal. Western Indo-Aryan languages are spoken in central, western, and northern India, Pakistan, and Afghanistan.
Dravidian languages are spoken by about 250 million people in India, Sri Lanka, Pakistan, Bangladesh, and Nepal. They are descended from a language that was spoken in India before the arrival of the Indo-Aryans. Dravidian languages are divided into four main branches: South Dravidian, Central Dravidian, North Dravidian, and Kurukh-Malto. South Dravidian languages are spoken in southern India. Central Dravidian languages are spoken in central India. North Dravidian languages are spoken in northern India. Kurukh-Malto languages are spoken in central India and Nepal.
Vajjika is a Dravidian language that is spoken in the Indian state of Bihar. It is closely related to the languages Kurukh and Malto. Vajjika is a minority language in India, and it is not officially recognized by the government. There are about 1 million speakers of Vajjika.