Correct option is C
Given:
Letters of the word "QUALITY"
Solution:

Arranging the letters of the word "QUALITY" in alphabetical order:
A, I, L, Q, T, U, Y
Positions of the letters change:
Q moves from the 1st position to the 4th position.
U moves from the 2nd position to the 6th position.
A moves from the 3rd position to the 1st position.
L moves from the 4th position to the 3rd position.
I moves from the 5th position to the 2nd position.
T moves from the 6th position to the 5th position.
Y stays in the 7th position.
So, the letter Y is the only letter whose position remains unchanged when the letters of the word QUALITY are arranged in alphabetical order.
Therefore, the position of one letter (Y) remains unchanged
Thus, correct option is (c)