Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:C
['B2 EB', 'ADFA EBEB BAFA', 'B2 eB', 'BAFA BAGF EFGE FB, (3B,B,B, FB,GB, BAGF']  
X:1
L:1/8
M:4/4
K:C
[M:4/4][K:Emin] _d[Q:1/8=360]"^part A" d^c | B2 EB FBed | B2 GB ADFA | B2 EB FBEA | dedB ADFA | 
 B2 EB FBed | B2 GB ADFA | B2 EB FBEA | dedB AGFD ||"^part B" EBEB BAFA | EBEe ADFA | EBEB BAFA | 
 dfdB ADFA | EBEB BAFA | EBEe ADFA | EBEB BAFA | dfdB AGFA ||"^part C" B2 eB fBeB | B2 eB ADFA | 
 (3BBB eB fBeB | dedB ADFA | B2 eB fBed | B2 eB ADFA | (3B^cd ea fbec | B^cdB ADFA || 
"^part D" BAGF EFGA | BE E2 BAFA | BAGF EFGE | FB, (3B,B,B, FB,GB, | BAGF EFGA | BE E2 BAFA | 
 (3B^cd ea fbec | B^cdB ADFA ||  