What term best describes the study of language in relation to the customs and needs of a community?

The term that best describes the study of language in relation to the customs and needs of a community is sociolinguistics. This field examines how social factors such as culture, ethnicity, gender, and socioeconomic status influence language use and variation. By focusing on the interplay between language and social contexts, sociolinguistics investigates how the language of a community is shaped by its customs and the identity of its members.

In contrast, the other terms in the list focus on different aspects of language. Semantics pertains to the meaning of words and phrases and how those meanings combine in language, but it does not specifically address the cultural context of usage. Psycholinguistics explores the relationship between language and cognitive processes, including how language is processed and understood by the brain, rather than focusing on social customs. Phonology is the study of the sound systems of languages, which examines how sounds function and pattern in particular languages, but again does not consider the social dimensions of language use within a community.