The correct option is A Explain Miss Nightingale's main concerns
Here, the primary purpose of the third paragraph is to explain what Florence Nightingale wanted to do and why. In this context, option C is the correct answer. D is too general – it refers to peacetime and wartime conditions but does not state that it is for the army, and so is incorrect. Option B is also too general – we are not concerned with hospitals in general, only the army. So, C is the best answer.