What is the focus of the field of semantics?

The field of semantics is centered on understanding the meaning of words, phrases, and sentences within a language. It explores how meaning is constructed, interpreted, and conveyed in various contexts. Semantics delves into concepts such as polysemy (the existence of multiple meanings for a word), synonymy (words with similar meanings), and antonymy (words with opposite meanings), among other aspects related to meaning.

In contrast, the other options focus on different linguistic fields. The study of sentence structure pertains to syntax, which examines how words combine to form phrases and sentences. The analysis of sound systems relates to phonetics and phonology, which investigate how sounds are produced and organized in language. Lastly, the exploration of language variation falls under sociolinguistics, which studies how language differs across social groups, regions, and contexts. Each of these areas contributes to the broader understanding of language, but semantics specifically targets the nuances of meaning, making it the correct answer.