(A)λ4π∈0asinπ4ˆi+λ4π∈0acosπ4ˆj(B)λ4π∈0a(1+sinπ4)ˆi+λ4π∈0acosπ4ˆj(C)λ4π∈0a(1−sinπ4)ˆi+λ4π∈0acosπ4ˆj(D)λ4π∈0asinπ4ˆi+λ4π∈0acosπ4ˆj