The correct answer is option 'C': Sinhala. Sinhala is the only official language of Sri Lanka. Let's explore this answer in detail.

Sinhala as the Official Language:
Sinhala, also known as Sinhalese, is the official and national language of Sri Lanka. It is spoken by the majority of the population, which makes it the most widely used language in the country. Sinhala is an Indo-Aryan language and is predominantly spoken by the Sinhalese ethnic group, who constitute the largest ethnic group in Sri Lanka.

Importance of Sinhala Language:
The status of Sinhala as the official language of Sri Lanka is rooted in historical and cultural factors. Sinhala has a rich literary history that dates back centuries, with ancient texts and inscriptions evidencing its usage. It has been the medium of communication, literature, and administration for the Sinhalese people for generations.

Language Policy in Sri Lanka:
The language policy in Sri Lanka has been a complex and sensitive issue due to the ethnic diversity of the country. Tamil is another significant language spoken in Sri Lanka, mainly by the Tamil ethnic minority. However, Sinhala was established as the sole official language in 1956 through the Official Language Act, which was a controversial decision at the time. This policy had an impact on the Tamil-speaking minority, leading to tensions and conflicts.

Bilingual Policy:
In response to the language issue and to promote inclusivity, the Sri Lankan government introduced the Sinhala-Tamil Bilingual Policy in 1987. According to this policy, both Sinhala and Tamil are recognized as national languages, and citizens have the right to access government services in their preferred language. Efforts have been made to provide bilingual services, especially in areas with a significant Tamil-speaking population.

Conclusion:
In conclusion, Sinhala is the only official language of Sri Lanka. It is deeply rooted in the cultural and historical fabric of the country. While there are other languages spoken in Sri Lanka, Sinhala holds the official status and is widely used for administration and communication purposes. The Sri Lankan government has also implemented measures to promote bilingualism and inclusivity through the Sinhala-Tamil Bilingual Policy.