Answer:
B) BD
Explanation:
The number of columns of the first matrix (2nd dimension) must match the number of rows of the second matrix (1st dimension). When you write the dimensions together, the two middle numbers must be the same.
AB ⇒ (3x2) × (3x5) . . . . 2 ≠ 3, so cannot be multiplied
BD ⇒ (3x5) × (5x7) . . . . 5 = 5, so can be multiplied
CD ⇒ (2x3) × (5x7) . . . . 3 ≠ 5, so cannot be multiplied
DD ⇒ (3x5) × (3x5) . . . . 3 ≠ 5, so cannot be multiplied