Answer:
TRUE
Step-by-step explanation:
A phoneme is often defined as the smallest unit of speech which makes it possible for us to distinguish one word from another. For instance, the difference between "grow" and "crow" lies in the phonemes /g/ and /c/.
A vowel digraph happens when we use two written vowels to produce only one phoneme. Think, for example, of the word "moon". We use two vowels "o" to produce only one sound, which is a long /u/. Therefore, the affirmation in the question is TRUE.