for multiplication under commutative then its must follow the rule AB=BA
for multiplication , matrices must be identity matrix then it will follow commutative property.
for matrix1= det(cosθ*cosθ+sinθ*sinθ=1) for this θ=nπ. to become identity matrix.
for matrix2=det(a*b=1) for this a=b=1 because then it will become identity matrix.
so option A is correct.