Orthography is best defined as:

The correct definition of orthography is indeed related to the system for representing oral language in writing. Orthography encompasses the conventions of spelling and writing that dictate how words are formed, including aspects such as the correct arrangement of letters, punctuation, and capitalization. It plays a crucial role in literacy development, as understanding these conventions enables students to read and write effectively.

The study of meaning in language corresponds more closely to semantics, which is the branch of linguistics concerned with meaning. The sounds and rhythms of speech relate to phonetics and phonology, which examine the auditory aspects of language, while the use of gestures in communication pertains to non-verbal communication or kinesics. Each of these areas, while important in the broader context of language, does not define orthography, making the choice that focuses on the written representation of language the most accurate.