Notice that 11 is between 3^2 and 4^2, so \sqrt{11} is between 3 and 4. We can estimate \sqrt{11} as 3.5, plugging that into the expression gives \sqrt{19} - \sqrt{5}.

Note that 19 is between 4^2 and 5^2, and 5 is between 2^2 and 3^2. So \sqrt{19} is between 4 and 5, \sqrt{5} is between 2 and 3. This means that we are looking for an answer that is between 1 and 3 (taking the min/max range of our guesses)

Looking at the answer choices, A is the only choice that falls in that range