"A particular form of a language which is peculiar to a specific region or social group." (Google dictionary). So I would say the answer is A. But C is also a reasonable answer.
The most accurate option is<em> Dialect is</em><em> A. language sounds of particular region. </em>
Explanation:
In a wider sense, <u>dialect</u> refers to a variety of language that people speak in a specific region. This variety is usually distinguished from others by grammar, vocabulary and pronunciation features. Therefore, the most accurate answer is A.