Answer A is the correct answer because every situation differs. Whats constant in all emergency driving situations, is the need to assess your options and make the decision that will result in the best outcome for everyone.
Answer B is incorrect because sometimes a short stop is needed to avoid an accident.
Answer C is incorrect because without thinking your reaction through, your first reaction may well be the worst possible reaction, like slamming on the breaks while in a skid.
Answer D is incorrect because not every situation calls for or would be helped by hitting the breaks. In some cases, switching lanes, or even speeding up is warranted. Immediately applying your breaks could result in an accident if the situation hasnt been properly assessed.