Which matrix product is defined?
(1×2)×(3×4)(1 \times 2) \times (3 \times 4)(1×2)×(3×4)
(3×2)×(3×2)(3 \times 2) \times (3 \times 2)(3×2)×(3×2)
(2×3)×(2×3)(2 \times 3) \times (2 \times 3)(2×3)×(2×3)
(2×3)×(3×4)(2 \times 3) \times (3 \times 4)(2×3)×(3×4)