Which of the following is NOT part of the ordinary of the Mass?

The ordinary of the Mass refers to the parts of the liturgy that are consistent and remain the same in every Mass, regardless of the season or occasion. These components include the Kyrie, Gloria, Credo, Sanctus, and Agnus Dei. In contrast, the Alleluia is considered a part of the proper of the Mass, which varies according to the liturgical calendar and specific celebrations. The Alleluia serves as a piece of music or chant performed before the Gospel reading, reflecting the joyous anticipation of the proclamation of Jesus' teachings, but it is not a fixed element that is present in every Mass. Therefore, identifying the Alleluia as not being part of the ordinary of the Mass is accurate, as it does not consistently appear across all celebrations of the Mass.