Which of the following definitions of linguistic terms are correct?
A. Orthoepy is the study of correct grammar in conformity with established regional patterns.
B. Philology is the study of phonemes and other characteristics of the systems of speech sounds in individual languages.
C. Synchronic study pertains to the study of language at a specific historical point.
D. Diachronic study pertains to historical dimensions of language i.e., linguistic change over the period of time.
E. Phonology is the study of language in its cultural and social contexts.
Choose the correct answer from the options given below:

The correct option is C and D only.

To understand why this option is correct, let us analyze the definitions of each linguistic term provided in the statements:

A. Orthoepy: Orthoepy is defined as the study of correct pronunciation of a language, not correct grammar in conformity with established regional patterns. Therefore, statement A is incorrect.

B. Philology: Philology is the study of language in oral and written historical sources; it is a combination of literary studies, history, and linguistics. The study of phonemes and systems of speech sounds is actually called Phonology. Therefore, statement B is incorrect.

C. Synchronic study: In linguistics, a synchronic approach analyzes a language at a specific, single point in time (usually the present), without considering its historical development. Therefore, statement C is correct.

D. Diachronic study: A diachronic approach (historical linguistics) studies the development and evolution of a language through history, focusing on linguistic change over time. Therefore, statement D is correct.

E. Phonology: As noted above, Phonology is the study of the speech sounds (phonemes) of a language. The study of language in its cultural and social contexts is known as Sociolinguistics. Therefore, statement E is incorrect.

Since only statements C and D are correct, the correct answer is C and D only.