Final answer:
The three nasal phonemes are /m/, /n/, and /ŋ/, characterized by the airflow being allowed to escape through the nasal cavity during their production.
Step-by-step explanation:
The three nasal phonemes are /m/, /n/, and /ŋ/. These sounds are called nasal because they are produced by releasing air through the nose. Unlike plosive, voiced, or fricative phonemes, nasal sounds are characterized by the airflow being allowed to escape through the nasal cavity. Examples of words containing these nasal phonemes include "moon" for /m/, "noon" for /n/, and "sing" for /ŋ/.