Using your knowledge of m/v = g/mL, you can start by putting that in the equation as:

And you know that the volume is 25 mL. So you could put this into the equation as:

And you also know that the molar mass of KCl is 74.55g (K = 39.1 g/mol and Cl = 35.45 g/mol. Add them together to get 74.55g/mol).
We can then put this in the equation as:

Then, we can mulitply them all together:

And now we know that
there are 0.01 moles of KCl in the sample.
In this question, the right doctor to operate your eyes would be Paula. Because Paula is a doctor for so many years already, it is suggested that Paula will be the right choice to operate because she has done so many operations already and she is more flexible and she can strategize more during operations because of the years of her experience.
the answer is C. distinguish himself from radicals.