Produce a musical expression that follows the indicated alphabetical structure while integrating the provided thematic material.
X:1
L:1/8
M:4/4
K:D
['B/c/B AG EA A2', 'a2 ag eaaf']  
X:1
L:1/8
M:4/4
K:D
 B/c/B AG EA A2 | G2 BG dGBG | B/c/B AG EA A2 | gedB BA A2 :| a2 ag eaaf | geed efge | a2 ag eaaf | 
 gedB BA A2 | a2 ag eaaf | geed ef g2 | bgag egfa | gedB BA A2 ||  