Which of the following is a union of two characters representing a single sound?

The correct answer is a digraph. A digraph refers to a pair of characters (letters) that together represent a single sound (phoneme) in a given language. For example, in English, the combination of letters "ch," as in "chocolate," creates a unique sound that is different from the individual sounds made by the letters "c" and "h" when they stand alone.

Understanding the role of digraphs is important in phonics and literacy development, as they help learners recognize and pronounce words accurately. This concept is foundational in teaching reading and spelling skills.

In contrast, consonant clusters involve two or more consonants occurring together in a word without any intervening vowels, producing individual sounds for each consonant. Diphthongs are complex vowel sounds that begin with one vowel sound and glide into another within the same syllable, rather than being formed by two letters representing a single sound. A phonogram is a written symbol or group of symbols representing a sound or group of sounds but does not specifically refer to the union of two characters.

Therefore, focusing on how digraphs function reinforces the understanding of sound patterns necessary for reading and phonics instruction.