"Corpus Christi" Plays Are So Called Because

"Corpus Christi" plays are so called because

A) they were commonly performed during the church festival of Corpus Christi some time between late May and late June.
B) the theme of the play always involved an analysis of the position of the church.
C) they were named after the author,Desiderius Corpus.
D) before the play began,a priest celebrated the Mass,a central feature of which was the transubstantiation,or symbolic creation,of Christ's body.