A) $A = 1{^\circ}$ structure, B = $2{^\circ}$ structure, C = $3{^\circ}$ structure, D = $4{^\circ}$ structure
B) $A = 4{^\circ}$ structure, B = $2{^\circ}$ structure, C = $3{^\circ}$ structure, D = $1{^\circ}$ structure
C) $A = 1{^\circ}$ structure, B = $4{^\circ}$ sstructure, C = $3{^\circ}$ structure, D = $2{^\circ}$ structure
D) $A = 4{^\circ}$ structure, B = $3{^\circ}$ structure, C = $2{^\circ}$ structure, D = $1{^\circ}$ structure