The correct answer is Hindi.
Hindi is the primary medium of instruction in most government schools in Haryana. This is because Hindi is the official language of Haryana and is spoken by the majority of the population. English is also taught in government schools, but it is not the primary medium of instruction. Haryanvi and Punjabi are spoken by a minority of the population in Haryana, and they are not taught in government schools.
Hindi is an Indo-Aryan language spoken by about 422 million people in India and around the world. It is the official language of India and is one of the 22 scheduled languages of India. Hindi is also the official language of the states of Haryana, Himachal Pradesh, Jammu and Kashmir, Jharkhand, Madhya Pradesh, Rajasthan, Uttarakhand, and Uttar Pradesh.
English is a West Germanic language that was first spoken in early medieval England and is now a global lingua franca. Named after the Angles, one of the Germanic tribes that migrated to England, it ultimately derives its name from the Anglia peninsula in the Baltic Sea. It is closely related to the Frisian languages, but its vocabulary has been significantly influenced by other Germanic languages, particularly Norse (a North Germanic language), as well as by Latin and French.
Haryanvi is an Indo-Aryan language spoken by about 6 million people in the Indian state of Haryana. It is closely related to Punjabi and Rajasthani. Haryanvi is not an official language of India, but it is recognized as a regional language in Haryana.
Punjabi is an Indo-Aryan language spoken by about 30 million people in the Indian states of Punjab and Haryana, and in the Pakistani provinces of Punjab and Khyber Pakhtunkhwa. It is also spoken by significant populations in Afghanistan, the United Kingdom, Canada, the United States, Australia, and New Zealand. Punjabi is the official language of the Indian state of Punjab and is one of the 22 scheduled languages of India.