The correct answer is A . K represents a speech sound and is a unit of an alphabet.
Letters in the alphabet represent symbols that we write, but the sounds are usually pronounced differently. For this reason, there is also the international phonetic alphabet, or IPA, which was developed in the 19th century to represent the pronunciation of sounds through symbols.
There are two groups of sounds in the phonetic alphabet: vowels and consonants. Most of the letters in the English alphabet do not match the speech sound symbols in the phonetic alphabet.
One exception to this is K, which is both a letter in the English alphabet and a symbol for speech sound in the IPA.
It is critical to note that the IPA applies only to languages that use the Latin alphabet, such as English. The representation of sounds in Arabic, Asian, Eastern European, and other languages would be different. More information on the IPA can be found here.