Let $A$ and $B$ be two matrices such that the order of $A$ is $5\times 7.$ If $A^{T}B$ and $B{A}^T$ are both defined, then (where $A^T$ is the transpose of matrix $A$)

• A

  order of $B^T$ is $5\times 7$
• Correct answer
  B

  order of $B^{T}A$ is $7\times 7$
• C

  order of $B^{T}A$ is $5\times 5$
• D

  $B^{T}A$ is undefined

Hence, the correct answer is option: 'B'.