Which of the following sounds is produced with relatively little constriction of the vocal tract?

Glides are produced with relatively little constriction of the vocal tract, allowing for a smooth flow of air. In glides, the articulators move from a near-open position to another vowel-like position, resulting in sounds that are acoustically similar to vowels but function as consonants in specific contexts. This smooth transition and minimal constriction create a characteristic sound quality that is more open than that of other consonants.

In contrast, affricates, fricatives, and stops involve more significant constriction or closure of the vocal tract. Affricates combine a stop and a fricative, leading to a complete constriction followed by a release. Fricatives are produced by forcing air through a narrow channel, creating turbulent airflow, which results in more constricting qualities. Stops involve a complete closure of the vocal tract before the release of air pressure, leading to a significant constriction. Thus, the nature of glides sets them apart as being less constrictive relative to the other sound categories listed.