Which of the following is NOT a focus of linguistics?

The focus of linguistics lies primarily in understanding language as a system of communication, which includes various components such as sounds, structures, and meanings. The study of human races is not related to linguistics; instead, it pertains to fields like anthropology or sociology that examine the biological and cultural aspects of human diversity.

Linguistics encompasses several specific areas, such as phonetics and phonology, which address the sounds of languages, and syntax and morphology, which look at the structure of language. Semantics and pragmatics delve into the meaning of language and its use in context. Thus, while the study of human races may intersect with cultural and social linguistics when language is a feature of identity, it is not a core focus of linguistics itself, making it the correct answer in this context.