The correct answer is C. Hindi.
Hindi is the official language of Himachal Pradesh. It is the most widely spoken language in the state, with over 90% of the population speaking it as their first language. Hindi is used in government, education, and the media. It is also the language of inter-state communication in Himachal Pradesh.
Punjabi is the second most widely spoken language in Himachal Pradesh, with over 8% of the population speaking it as their first language. Punjabi is used in government, education, and the media in some parts of the state.
Pahari is a group of languages spoken in the Himalayas. There are many different dialects of Pahari, and it is not a single language. Pahari is spoken by about 10% of the population of Himachal Pradesh.
Kangri is a dialect of Pahari spoken in the Kangra district of Himachal Pradesh. It is spoken by about 2% of the population of the state.
The other options are incorrect because they are not the official language of Himachal Pradesh.