It looks like there's a typo in the question:
The "U" in LESIRU looks like it should be a "V"
If so, here is how I solved it:
I assigned each letter a number in the order it appears in the initial word, making it 123456. Then I looked at the scrambled word to see where the letters ended up, and wrote down the numbers of each letter in their scrambled order (such as 253641, for example, though this wasn't it). Then I compared the two scrambled number-words to see if they were the same. When they were, then I knew the third would follow the same pattern.
Then the answer is:
D. If the letters in the words are replaced with numbers, so that the word becomes 123456, then the scrambled state is 351264. That is, write the 3rd letter, then the 5th, then the 1st, 2nd, 6th and 4th.