Develop a musical composition using the outlined alphabetical depiction of the structure and the provided theme.
X:1
L:1/8
M:6/8
K:Fmix
['E C2', 'E C2']  
X:1
L:1/8
M:6/8
K:Fmix
 C2 D | E2 E C2"^(a)" C | ED E C2 z | F=E F GAB | A2 G !fermata!F2 G | c2 B"^(b)" c2 A | 
 BA G c2 B | c2 F F2 G | F2 E C2 D | ED E C2 D | ED E C2 z | F=E F GAB |"^(c)" A2 G !fermata!F3 || 
 C2 D | E2 E C2"^(a) var." D | ED E C2 z | F=E F GAB | A2 G !fermata!F2 G | c2 B"^(b) var." cBA | 
 B2 G c2 B | c2 F F2 G | F2 E C2 D | ED E C2 D | ED E C2 z | F=E F GAB | 
"^(c) var." AG A !fermata!F3 |]  