When you multiply a fraction, you do the top and the bottom separately, right?
Since a square root is like the opposite of multiplying, you can think of the top and the bottom separately for this too!
First, let's start with the top. The square root of 1 is 1, so the numerator is 1.
Now, let's do the bottom. The square root of 121 is 11, so the denominator is 11.
So, the answer is D, 1/11. You can check your answer by squaring it, and getting 1/121.
Hope this helps!