Answer:
The answer is option (a) permutation of data at byte level.
Step-by-step explanation:
Solution
During the process of AES (Advanced encryption Standard) algorithm, these two steps shift rows and mix columns are two sub-steps of process, in which, shift row works on rows and basically shifts nth row by n-1 bytes to left side, that is, the first row will not shift at all, the second row by one place shift left, and apart from it mix columns works on columns. in this each column is transformed with a particular function, so these two steps are very different.