Given two matrices A and B which you can multiply together, does (A B)^T = A^T B^T or B^T A^T?
When you multiply two matrices A and B and then take the transpose of the product, the result is equal to the product of the transposes of the individual matrices, but in reverse order. In other words, if you can multiply A and B together, then:

(A B)^T = B^T A^T