Final answer:
The study of articulatory features of language is phonology, which focuses on the physical processes of sound production in language.
Step-by-step explanation:
The study of the articulatory features of language, such as how lips and tongue are formed to produce certain speech sounds, is phonology. Phonology is a subfield of linguistics that examines the sound systems of languages, including the way in which individual sounds are produced. Syntax is the arrangement of words in a sentence, semantics is the study of meaning, and pragmatics analyzes language usage in context, but none of these are focused on physical articulatory processes. Thus, the correct option is a) Phonology.