The correct answer is: a) English.
English is the primary medium of instruction in most government schools in Meghalaya. This is because English is the official language of Meghalaya and is widely spoken in the state. It is also the language of instruction in higher education and in the government.
Khasi and Garo are the two major tribal languages of Meghalaya. They are spoken by about 50% of the population of the state. However, they are not used as the medium of instruction in government schools.
Hindi is the national language of India. It is spoken by about 40% of the population of India. However, it is not widely spoken in Meghalaya. It is also not used as the medium of instruction in government schools.
Bengali is a major language of India. It is spoken by about 26% of the population of India. However, it is not widely spoken in Meghalaya. It is also not used as the medium of instruction in government schools.