Which of these composers is not part of the traditional mass composition lineage?

The correct answer is Weber, as he is generally not associated with the traditional mass composition lineage that prominently features composers who wrote in the style and context of Roman Catholic liturgical music.

Palestrina is considered a key figure in the development of sacred music and is renowned for his contributions to the mass form during the Renaissance. His compositions exemplify the clarity and balance characteristic of that period, making him a pivotal composer in this lineage.

Mozart, although known for a wide range of musical genres, made significant contributions to the mass form with works like the “Great Mass in C minor.” He combined classical elegance with the sacred traditions of the mass, solidifying his place in its historical context.

Berlioz, while a Romantic composer, also engaged with or inspired by the tradition of mass composition, particularly in his work “Te Deum.” Even though his style was markedly different, his involvement with liturgical music still connects him to the broader history of mass composition.

In contrast, Weber's primary contributions lay in the realm of opera and symphonic music, and although he wrote minor sacred pieces, he is not recognized as a significant figure in the traditional mass composition lineage.